If you have multiple workbooks in Excel that you need to password protect, using a single password for all of them can save you time and hassle. Here's how to do it:

1. Open the first workbook that you want to password protect.
2. Click the "File" tab, then click "Save As."
3. In the "Save As" dialog box, click the "Tools" drop-down menu and select "General Options."
4. In the "General Options" dialog box, enter the password in the "Password to open" field and click "OK."
5. Re-enter the password in the "Confirm Password" field and click "OK."
6. Click "Save."
7. Repeat steps 1-7 for each additional workbook that you want to password protect.