Timesheets in the draft state (or in the rejected state) can be amended by the timesheet submitter as many times as they want. Once submitted however, they become locked and can no longer be modified.

To make changes to a timesheet after it has been submitted / approved, you must be an administrator or you need the Edit Timesheets role. Go to the Timesheet Management page, and on this page, you can view a list of all your recent timesheets, which can also be filtered by date. It is best to change the view mode on top to "Timesheet Summaries" to avoid cluttering the view with lots of detail.

To make changes to a timesheet, click on the edit icon (the pencil) on the right hand side of the timesheet. You can now make changes to any of the aspects of the timesheet. If you want the original submitter to make the changes, then you can just alter the timesheet status field (shown on the top left of the timesheet) back to Draft status and allow them to make the changes. If you want to make the changes yourself (or if you are an administrator and you need to change your own timesheet) then you can simply amend the timesheet as required. When you have completed your amendments, ensure you click on "Save Changes" in the timesheet footer.