If you close and reopen Thunderbird a screen should pop up asking for password. Enter it there. If you don't get that popup. On the top bar click the three lines on the right side. From the list that appears click '''Settings'''. On the page that shows click the '''Privacy & Security''' line on the left side. On the new page that shows click '''Saved Passwords...''' button. You will get a box listing your email accounts. Click show password button to see current passwords. Click on line you want to edit. Then Right click for edit.