A quick way would be to option the date field to time stamp the field whenever the record is modified. If you don't want that, then a trigger script can be used to trigger every time the 'amount " is modified. The script should go like this:
Set Field[Date field}; Get(currentDate)] and the trigger should be set at field Modification, Save or Exit.
You can create an auto-enter calculation within you date field.
Set it to always update ( uncheck "Do not replace existing value..."
The trick is to write a calculation that references your trigger field:
trigger = Amount ;
Get ( CurrentDate )
Whenever the Amount field will get updated, the Date field will update as well because it has a reference to the Amount field.
electon's solution is a better one
electon & yomango thanks for the support -I used "elections" suggestion -that worked pretty fine for me -once again thank you very much <3