Personal Vault will automatically lock after 20 minutes of inactivity by default. You can select to automatically lock your Personal Vault after 20 minutes, 1 hour, 2 hours, or 4 hours of inactivity. You can manually lock and unlock your Personal Vault at any time.
Click on the OneDrive notification icon on the taskbar system tray > Help & Settings (gear) button > Settings.
Open your OneDrive folder in File Explorer > click on OneDrive on the command bar > click on the Settings (gear) button > Click on the Account in the left pane of OneDrive settings >Select 20 Minutes (default), 1 Hour, 2 Hours, or 4 Hours in the "Lock Personal Vault after" drop menu