The article only describes how to change the password specified in the mail client. To change the password directly for the mailbox itself, use
instruction.
To change your password mailbox in Thunderbird, do the following:
Open the main Thunderbird menu and go to the "
Settings → Settings»:

Go to the section "
Protection", Switch to the"
Passwords" and press "
Saved passwords…»:

Click "
Show passwords"And confirm the operation:

Right-click on the line with the address of the required mailbox, select from the context menu "
Change Password»And specify a new password (for each mailbox you need to specify it in two lines - for IMAP or POP3 and for SMTP):

Restart Thunderbird.
Alternatively, you can in the window "Saved logins"Or select the lines with the name of the required mailbox in the list and press"Delete", Or if you need to change the password for all mailboxes added to Thunderbird, use the"Delete everything»:
After confirming the operation and restarting Thunderbird, the first time you connect to the mail server, the mail client will automatically ask for a new password: