Changing a rule or process in TM1 does not show up in the logs.
That is fine as long as you are the only Power User able to tinker with these objects.
Unfortunately, it can get out of hand pretty quickly as more power users join the party and make changes that might impact other departments data.
So here goes a simple way to report changes.

The idea is to compare the current files on the production server with a backup from the previous day.

You will need:

A quick way to monitor users login/logout on your system is to log the STATUS value (i.e. ACTIVE or blank) from the }ClientProperties cube.

View->Display Control Objects
Cubes -rightclick- Security Assignments
browse down to the }ClientProperties cube and make sure the Logging box is checked
tm1server -rightclick- View Transaction Log
Select Cubes: }ClientProperties