Go to the Maintenance tab and in the search box for admin log search for Updated, this will give you list of profiles updated in the ACP. Note that someone could of deleted the log entry if they have those permissions.
This happened to all administrators on that board last time.
Having multiple founders defeats the purpose of having a founder. There is no reason someone given admin permissions needs founder status, even your main account doesn't need founder status.
You should need no more than three. Yourself, optionally a stealth account and optionally someone you have utmost trust in. The stealth account is fail safe or can even be used as only founder. The founder status for someone else is in case you get hit by a bus.
“Results! Why, man, I have gotten a lot of results! I have found several thousand things that won’t work.”
Attributed - Thomas Edison