Although more secure than right-clicking a tab and clicking "Hide," making a worksheet very hidden isn't a fail-safe method ...

Select the budget worksheet tab (Quarter, Trimester, Semester, or Annual) matching your academic terms. Estimated budget amounts are pre-filled for Undergraduates in the Quarter calendar. Review ...

Click the check box of the Developer tab, then OK. You will see a developer tab in the menu of the worksheet. The Design Mode will turn on, and you will see a plus sign on the worksheet.