The reason is because Electrum (mobile version) since version 4.1.0 no longer allow users to set different passwords for different wallets. So, if you update the password for one of your wallets (the watch-only in this case), all your other wallets will be encrypted with that new unified password.
I would like to correct this since it's possible to set a different password per wallet in Mobile Electrum version.
So their suggestion to use an easy generic password is viable.
Probably because the steps are quite hidden, here's how sit can be done:
- After Opening Electrum, if there's any existing wallet, it'll prompt you to type the password.
- Do not type anything, instead, tap outside of that window and you'll directly enter Electrum GUI without any loaded wallet.
- Create a new wallet, in the last step, you'll be prompted to set a password that can be different from other wallet's password.
- After having two wallets with different passwords, the "unified password" feature will fail its initial check and set that your existing wallets and new wallets can have different passwords.
I think the confusion was caused by the new QML GUI that failed to port some of the unified password features should change the texts in the passwords field if it's disabled.
Here's how it should've behaved:
Whether the password is unified can be seen in the GUI: In the
'Settings' dialog, the description for the password setting is
'Change password for this wallet' if the password is not unified,
and becomes 'Change password' if password is unified.