I have a Microsoft Office 365 account I access through IMAP in Thunderbird. None of the Thunderbird "save local copies/archive/etc." options seem to actually work like they did for my Yahoo POP3 account, which could be related to my real problem, but I haven't tried too hard to fix that because downloading all the emails gives me offline access anyway. Now the real problem:

Whenever I change my password through the Office 365 webpage, the next time I open Thunderbird it tries to access that account before I can stop it, gets the wrong password, and then deletes its entire cache of my emails, so it has to redownload them once I put the right password into Thunderbird. This redownloading takes forever. How can I stop it from deleting them in the first place?