All the Photoshop tool settings are "sticky" and should remain at the last setting. If your settings mysteriously change or revert, then something on your system is doing it.
If you reset preferences, that would do it. The next suspect is Actions. It's possible that some 3rd party action you've downloaded is messing with the tool settings.
I had that happen once. A downloaded action was making custom Text tool settings, changing my Text to vertical. Was an action I ran very infrequently and I use the Text tool very infrequently, so was hard to find.
When I finally found it, the Text tool setting in the action had absolutely nothing to do with the intent of the action. I figured the author was just sloppy, and developed the action from a clone of some other action, and forgot to clean it up.
So a tip to search for such things...
Save your actions as text files, then use a text editor to search for the appropriate string that indicates a clone tool setting.
