Second issue first... one thing that can cause settings to not be saved is if the file that holds most of your preferences ("prefs.js") somehow gets marked by the operating system as Read Only. That's not normal, and there's no good reason for it to happen, but it sometimes does (one possible BAD reason could be hard disk corruption, so you should check into that ASAP.) If using Windows, the file will usually be found at C:\Users\<your user name>\AppData\Roaming\Mozilla\Firefox\Profiles\<your profile name>\prefs.js With Thunderbird closed, right-click on the name in File Explorer and choose Properties. Is the Read-only attribute box checked? If so, uncheck it and press OK. Now start Thunderbird and test to see if your changes are now saved. ------------- First issue second... Got to Tools | Account Settings | Copies & Folders. Make sure the "When sending messages, automatically: [x] place a copy in" is enabled and points to a valid folder. Also, check that the "Place replies in the folder of the message being replied to" option is disabled.