When an entry is changed on an entry screen, it can be handled in several different ways depending upon the state of the sheet and the system setting for "Level of auditing required when users make changes to existing entries." Most of the time, you will not be aware of what the database is doing with changes as you make them. It will simply handle the changes "under the hood" as you update your entries. If your administrator has set your audit level to 3 or 5, you will be required to enter a reason for changing an existing entry on either a submitted or open sheet. Sheet status must be open or rejected in order to make changes.
Administrators and users whose role includes the Prior Period Corrections ability can make changes to entries on approved sheets. For these users, the Save Corrections button will appear on approved sheets. When this button is present, corrective entries can be entered in the blank rows at the bottom of the screen.