I went under Edit --> Preferences --> Saved Passwords --> Show Passwords

I have TB 60.9.0 on ubuntu 16.04 Today I had to change my gmail password via browser because I had forgotten it. Then Thunderbird started asking me for the gmail password (because it had still the old one saved). But it keeps asking for it each time I have to send a message or check emails. I went under Edit --> Preferences --> Saved Passwords --> Show Passwords and noticed in fact that it had the old password saved. I then REMOVED the gmail lines, restarted TB, it asked me the passwd, put in the new one. But it keeps asking for it. I checked Edit --> Preferences --> Saved Passwords --> Show Passwords and noticed that it did not save the new information. What can I do? thanks.