Sounds like you are pasting in text that looks like dates. Pre-format as
text first.

Gustavo wrote:

Hello.

I apologize if duplicate, but tried looking for something similar in the
forum and didn't have luck.

Mi problem is that I have a file (new, not imported from a previous version)
that works fine until one point when all the numbers are changed in the
format from General to Date format. What can I do to prevent Excel of doing
this?

Thank you!