Arranging Opened Workbooks on Screen
Sounds simple, but this is one of the top questions I've been asked over the years. This is an essential skill every Excel user should learn.
The skills described in this tutorial is especially essential with these situation:
Case 1: If you have several workbooks (Excel files) opened in Excel, and you want to see them all at the same time on your screen.
Case 2: If the workbook tabs is not viewable (outside the screen or covered)
Click the Arrange All button in the Window group on the View tab.
The Arrange Windows dialog box appears.
Step 2 - Choose one of the arrangement options
The workbooks are arranged on-screen based on your selection in the previous step.
After you arrange windows, activate the one you want to use (if it's not already selected) by clicking it. In the case of the cascade arrangement, you need to click the worksheet window's title bar, or you can access the worksheet from the Windows taskbar.
If you close one of the windows you've arranged, Excel doesn't automatically resize the other open windows to fill in the gap. To fix this, click the Arrange All command again on the View tab, select the desired arrangement, and click OK. (More conveniently, you can first maximize one of the windows, they click Arrange All again.)