Excel 2016 automatically keeps a running list of the last 25 files you opened in the Recent Workbooks list on the Open screen when the Recent Workbooks option is selected under Places. If you want, you can have Excel display more or fewer files in this list.
To change the number of recently opened files that appear, follow these simple steps:
Choose File→Options→Advanced or press Alt+FTA to open the Advanced tab of the Excel Options dialog box.
Type a new entry (between 1 and 50) in the Show This Number of Recent Documents text box located in the Display section or use the spinner buttons to increase or decrease this number.
Click OK or press Enter to close the Excel Options dialog box.
If you don't want any files displayed in the Recent Workbooks list, either on the Excel or Open screen in the Backstage view, enter 0 in the Show This Number of Recent Documents text box or select it with the spinner buttons.
Select the Quickly Access This Number of Recent Workbooks check box on the Advanced tab of the Excel Options dialog box (right below the Show This Number of Recent Workbooks option) to have Excel display the four most recently opened workbooks as menu items at the bottom of the File menu in the Backstage view. That way, you can open any of them by clicking its button even when the Open screen is not displayed in the Backstage view.
If four workbook files is too many or not sufficient, you can decrease or increase the number of files shown at the bottom of the File menu by replacing 4 in the text box that appears to the right of the Quickly Access This Number of Recent Workbooks check box option.