How to Change How Long Until a Mac Asks for Your Password

Adjusting Your Screen Saver and Sleep Times

1. 
   Click the "Show All" button at the top of the window. This will return you to the System Preferences menu so that you can change the time until your computer goes to sleep or enables the screen saver.
2. 
   Click the "Desktop & Screen Saver" option.
3. 
   Click the "Screen Saver" tab.
4. 
   Click the "Start after" menu.
5. 
   Click the time that your screen saver should start. If you don't want a screen saver, select "Never." Your computer will prompt you for a password once the allotted time has passed after the screen saver activates.
6. 
   Click the "Show All" button. You'll now be changing the time until your computer puts itself to sleep.
7. 
   Click the "Energy Saver" option.
8. 
   Click and drag the "Computer sleep" slider. Your computer will put itself to sleep after this amount of inactivity. You'll then be prompted for your password however long after that, depending on what you set earlier in the Security & Privacy menu.