My Excel (365 64-bit) is constantly defaulting to 5-digit dates.

I already know how to change the date format of selected cells from 5-digits to a normal-looking date. But how do I stop it from defaulting to 5-digit dates in the first place? It happens under all sorts of circumstances... I'll change some data then update a table, and blam, all the dates that I had already changed to normal-looking dates have reset to 5-digit dates.

I have two colleagues who use copies of the exact same spreadsheets and pivots as me, yet their dates are always normal - their dates are never switched to 5-digit dates.

I've done piles of searches for a solution, but they all just explain how to convert the dates using Format Cells... but I don't want to have to do this 50 times/day (I'm not exaggerating). I want it to stop defaulting to 5-digit dates altogether.

Would greatly appreciate a solution!

Thanks,

Wayne