Quote from: Bright Light on June 07, 2021, 12:55:52 PM

How can I upgrade to Nested Segwit, addresses starting with 3 on Electrum.

I will not advice you to use many of the BIP39 wallets because they are close source, a wallet that its source code is not available for the public to check of vulnerabilities can not be trusted. If you want a nexted segwit wallet (wallets that its addresses starts from 3), you can visit https://iancoleman.io/bip39/ and generate it offline.

Access https://iancoleman.io/bip39/, turn off all internet connections on your device, open another tab, access the site again through the new tab with no internet connection, the site will open. Then, you can generate your seed phrase. Alternatively, which is the best is to run its html file offline, you can download the source from https://github.com/iancoleman/bip39/releases/latest/.

Import the seed phrase on electrum by clicking on:

Next
Standard wallet
I already have a seed

Input the seed phrase generated safely from Iancoleman, check "BIP39 seed to enable Next

click Next
p2sh-p2wpkh
Next
input password

With this, you will be able to generate nexted segwit keys and addresses also on electrum wallet, but know that the seed phrase is not stored on electrum, only the keys and addresses are stored. Make sure you have your backup offline. Also, the fee paid using native segwit (addresses that start from bc1) in transactions is still very low if compared to nested segwit, so I will still advice you to use native segwit which electrum will generate by default. Also, you can decide to use open source wallet like mycelium, but I have not used it before, make sure the keys and addresses of the nested segwit are the same as that on electrum after importimg it.