How did you generate your seed phrase? What wallet/software did you use for that? Maybe, the address you are looking for has been generated on a different derivation path.
Did you try clicking on "Detect existing accounts"?

It's possible that a node has a different setting and keep a transaction in its mempool for a very long time. But that doesn't matter at all. The majority of nodes will probably drop the transaction from their mempool and OP will be able to broadcast a new transaction. The problem here is that coinbase may rebroadcast that transaction.


You can do CPFP if you have control over an output of the transaction. In other words, you need to have the private key of one of receiving addresses.
If you have withdrawn bitcoin from an exchange to an address you have full control over it, you are able to do CPFP. The problem is that withdrawal transactions made from exchanges usually have a large size and doing CPFP for them would be expensive.

No. By default, RBF is enabled and in the current version, it's not possible to disable it.
Note that the option to disable RBF was removed in the version 4.4.0. In the versions before that, you had the option to choose whether or not you want your transaction to be flagged as RBF.

A 12 word seed phrase is secure enough.
A 12 word BIP39 seed phrase provides 128 bits of security and since a private key provides 128 bits of entropy, 12 words are enough.

It may worth mentioning that you can generate a 24 word seed phrase using electrum too.  To do so, you need to go to console tab and use the following command.


Just note that a seed phrase generated by electrum isn't BIP39. Electrum uses its own algorithm.

You can't delete your topics and even if you could delete this topic, there was no need to do that.
As you have got the answer to your question, you may want to lock the topic. To do so, just scroll down and click on "lock topic" at bottom left corner of the page.

Each node has a mempool which includes unconfirmed transactions.
Being dropped from the mempool means that the node no longer keeps the transaction in its mempool.

When we say bitcoin transactions are irreverisble, we are talking about confirmed transactions. If a transaction is unconfirmed, it hasn't been included in the blockchain at all.


That's exactly why you shouldn't accept an unconfirmed transaction, if you don't trust the sender. There is no guarantee that an unconfirmed transaction will be finally confirmed.

The decision was made by theymos to decrease spam. Read the post quoted below for more information.

For using ViaBTC free accelerator, the fee rate must be equal or greater than 10 sat/byte. The fee rate used for OP's transaction is around 8.8 sat/byte.
The other problem is that the transaction in question has unconfirmed parents and their free service doesn't accelerate such transactions.

It's not possible to do CPFP.
According to transaction history of the receiving address, it probably belongs to a custodial service like an exchange.

If a transaction has been flagged as RBF, you can bump the fee. Bumping the fee means that you replace an unconfirmed transaction with a new one paying higher fee without any need to wait for the tranaction to be dropped from the mempool.
By default, Electrum flag transactions as RBF.


You will see your unconfirmed transaction on electrum, but since it hasn't been flagged as RBF, you won't be able to bump its fee.
As already said, you will have to wait until your transaction is dropped from the mempool and then make a new transaction. Your new transaction can be a RBF-enabled transaction, so that you can bump its fee if required.

I suggest you to use electrum, so that you can make a RBF-enabled transaction.


In a SPV wallet like mycelium, synchronizing means getting required data from the server.


Different nodes have different setting. The default setting is that transactions are dropped from the mempool after two weeks. It's possible that a node drops your transaction from its mempool after two weeks while another node will still keep your transaction.
After two weeks, most nodes will probably drop your transaction from their mempool and most block explorers will no longer display your transaction.

I just checked your transaction on some block explorers and it seems that it has been last broadcasted 1 week ago. It should be dropped from mempool of most nodes 1 week later. (By default, transactions are dropped from the mempool after two weeks.)

Import your wallet into electrum. Wait until your transaction is dropped from the mempool and then make a new transaction on electrum. With electrum, you can make RBF-enabled transaction, so that you can bump the fee if required.

I am not sure, but I think mycelium rebroadcast transactions automatically. If that's the case, you need to delete your wallet, so that it no longer rebroadcast your transaction. Before deleting your wallet, make sure that you will be able to recover your wallet.

To know how many times you have played the free roll, go to "Stats" and then click on "Personal stats". You can also see how much you have earned through the faucet and some other statistics there.

There's a good discussion about this in the thread created by RickDeckard.
Ledger Recovery - Send your (encrypted) recovery phrase to 3rd parties entities

Correct.

I am not sure, but I think miners are free to place transactions in the block in any order they want.

The first number is the number of block in which the coin has been created.
The second number indicates the location of the transaction in the block. (It starts from 0)
The third number indicates the location of the output in the transaction. (It starts from 0)

790548x208x4 means that the coin has been created in block number 790548, in the transaction number 208 with output index of 4.
790551x2803x0 means that the coin has been created in block number 790551 in the transaction number 2803 with output index of 0.

I also tried that, but couldn't open the webpage.
The tweet says "here's a demo of our upcoming Mempool Accelerator". Maybe, they haven't launched their service yet.

That's because Betwrong has disabled getting lottery tickets.
You can go to your profile and check "Disable lottery" option. With doing so, you will get reward points instead of lottery tickets.

A thing you should know is that you can pay lower fee with using segwit addresses.

You made your transaction from a legacy address and it had the virtual size of 188 vbytes.
You could decrease the (virtual) size of your transaction to around 130 vbyte with using a nested segwit address (an address starting with 3) and to around 110 vbytes with using a native segwit address (an address starting with bc1q).

Note that electrum versions older than 3.3.4 are vulnerable to a phishing attack in which the server can display a message and ask you to download a fake version of electrum.
So, ignore any message you see on electrum asking you to update the wallet.

If you want to update electrum, go to its official website. Download electrum from there and don't forget to verify your download.


If you want to be completely secure, you should have your electrum wallet on an airgapped device. If your wallet has been already connected to the internet, I don't think that makes much difference whether you install the new version on the same device or not.

If you have two devices and you think one of them is more secure than the other one, it's obvious that you should use the more secure one.