Is there a simple way to log transactions?

Our municiaplity has been encouraging managers to automate which has
resulted in many creating Excel spreadsheets to store and display
data. They are not logging transactions (ie changes) so when the
auditor tries to figure out what's been going on there is no computer
record.

I've looked in the MS Excel manaul for a feature which logs
spreadsheet changes without success. Has anyone a solution, preferably
simple and easy to use, to this problem?

Thanks.