I placed two transactions but the remaining balance was not enough for both. At that time I was experimenting with the Coin control. Eventually, one got confirmed but the other remains unconfirmed. Is there any way to remove it from the mempool? The abandon option is not available and it is unconfirmed. Will the nodes of the network remove it at some point? For both of these transactions, the option replace by fee was enabled.

I sent an amount to an address and my transaction has as input multiple addresses of my wallet. As a result, most of the input addresses have a non-zero final balance after the transaction. Is this normal? I know that there is a security issue if you use an address as input and it still has a positive balance after the transaction. I have seen this topic explained by Antonopoulos but I don't know if it is an important security issue. Is there a way to make my used addresses to have 0 final balance?

In the following video, Vitalik explains why Graig's presentation makes no sense I can understand some of his points however I can not hear everything and I don't understand everything because I am not familiar with all the terms and definitions. Could you please write down for me what he said? For instance, he is talking about the percent of the network which colludes with a miner, he calls that "kyano" or something? Also, he says "for NP-hard problem we can implement heuristic solutions which are..."   what?  ".....near-optimal in practice"?

 https://www.youtube.com/watch?v=oeM8BuzeSTc

I created a backup wallet on pc by using Bitcoin Core version v0.18.0 (64-bit) and I was trying to restore it on my phone. However, the app can not recognize (or locate) the file. However, I can restore a wallet which is created by the app itself. Is the type of files different?

I just saw that there is another section for wallets in this forum but I can not delete or move my post to the correct section. Sorry for the inconvenience.