I try not to correct people when they’re speaking, but it isn’t always so easy to bite my tongue. The only thing I can do is try to get a read on person and situation and see if they would appreciate the help or be offended. More often than not, the person would be offended and so I keep my mouth shut.
The best way I’ve found to remember which to use is this: more than is for quantity and over is for jumping. The cow jumped over the moon.
Now there are some experts that claim that over has been used to describe quantity since Old English. The AP Stylebook disagrees. “Generally refers to spatial relationships,” and more than “is preferred with numerals.”
I’m going to go with the AP Stylebook on this one.