how do you identify the active file if more than one has been opened simultaneously and are being displayed on the screen

Explanation:

On the View tab, in the Window group, click New Window.

On the View tab, in the Window group, click View Side by Side .

In the workbook window, click the worksheets that you want to compare.

To scroll both worksheets at the same time, click Synchronous Scrolling in the Window group on the View tab.

Note This option is available only when View Side by Side is turned on.

Tips

If you resize the workbook windows for optimal viewing, you can click Reset Window Position to return to the original settings.

To restore a workbook window to full size, click Maximize at the upper-right corner of the workbook window.

View two worksheets of different workbooks side by side

Open both of the workbooks that contain the worksheets that you want to compare.

On the View tab, in the Window group, click View Side by Side.