Bitcoin Forum

Hello,

This is user interface of hardware wallet "Trezor One": https://imgur.com/iClqbfT

I would like to ask, if I create "new account" on hardware wallet, does it means that I generate also new seed for this new account (and all currenties which account contains) or I have only one seed pharse for whole
wallet with all accounts?
Thank you for reply

No, it's not going to generate a new seed for you. Everything is derived from the seed you first got when setting up the wallet. You can find the technical details here[1].

[1] https://wiki.trezor.io/Cryptocurrency_standards

As OmegaStarScream says, the new account will be under the same seed phrase.

Your first segwit bitcoin account is derived at the following path: m/84'/0'/0'
If you create a second segwit bitcoin account, it will be derived at: m/84'/0'/1'
If you create a legacy bitcoin account, it will be derived at: m/44'/0'/0'
If you create a second legacy bitcoin account, it will be derived at: m/44'/0'/1'

And so on. Segwit accounts are at 84', legacy accounts are at 44', and the the third number is incremented by 1 for every new account you create.

Your "Add account" button is grayed out because your current account is empty. Trezor will not let you create a second (or third, or so on) account until the previous account has been funded.

Trezor is using same seed words when you create new accounts, and you can also add multiple passphrases as a soil for creating new hidden accounts for improving security.
You can always reset and wipe your Trezor device and generate (or import) new seed words with new accounts, just keep backup words safe on paper or metal plates.
Not that I think they have some limitation for creating up to ten accounts for each cryptocurrency in your wallet.
They recently added custom backgrounds so you can make difference between accounts much easier.

Now this is clear to me in the case of bitcoin.

But how does this work in the case of different crypto currencies and completely different blockchains?

When creating an account on any HW wallet (can be Trezor or from any other manufacturer), seed-phrase is generated. One single seed-phrase, but on a device we can create hundreds of wallets. I mean wallets with different crypto currencies standards: BTC, ETH, XMR, etc. How is it technically arranged?

Imagine the situation: need to restore from HW wallet (from device with the same seed-phrase), which stored crypto currencies with different standards (for example, electrum with BTC, myetherwallet with ETH, Monero GUI Wallet with XMR). Is it enough to enter into each of these wallets (electrum, myetherwallet, Monero GUI Wallet) that wash and the only seed-phrase from HW wallet?

Can I get at least a superficial explanation of how it works?

The same seed phrase from your hardware wallet can be restored in each of those coin's other software wallets if they support importing seed phrases. The other piece of info that is essential is the derivation path. You need to use the same derivation path in the second wallet that you used in the original one. Some wallets use a non-standard derivation path or even try to hide the path for some reason. This can prove to be troublesome if you need to recover from seed on a different client. 

Generally, all multicurrency wallets use standard derivation path, which is defined in BIP44:

m / purpose' / coin_type' / account' / change / address_index

coin_type is a constant (number), which defines for which cryptocurrency we are creating account.

The list of all registered coin types can be found here: https://github.com/satoshilabs/slips/blob/master/slip-0044.md

With coin type we can handle thousands of different cryptocurrencies, because each subtree (produced by different coin type numbers) will result in a separate set of keys and addresses.

You can check out this info-graphic to find out more.

so, your actual keys used for addresses are in lowest level of the tree.

Source: https://learnmeabitcoin.com/technical/derivation-paths

by using iancoleman.io website (work offline) you can see all the addresses that are being generated.

Some closed source wallets hide Path, then you need to download their software.