To fix an already finished score sheet:
Go to Calendar (Menu > Manage > Schedule/Charts > Calendar).
1. Find the match you need to fix. (Use the two small calendars on the left hand side to find the match you are looking for.)
2. Select the match by clicking on it once.
3. Click on Score.
4. Click on Set as Not Finished to unlock the scoresheet.
5. Make the proper changes.
6. Click on Finish Match to lock it back up.
Players don't have the ability to do this. If they need to fix a scoresheet, they need to reach a League Operator to do so.
A league operator can choose to fix it themselves or send the scoresheet back out for them to fix it.