MAC OS Screen Saver/Lock Settings

Open "System Preferences"

Via the Apple Menu

Via the Dock

From "System Preferences", open the "Desktop & Screen Saver" panel

Select the Screen Saver tab

 Set delay before starting Screen Saver at 15 minutes or less

(Optional) Click the "Hot Corners ..." button

Pick a screen corner and change the action to “Start Screen Saver”

Moving the pointer to that corner will lock the screen

Closing the laptop lid will lock the screen and cause the system to hibernate

From "System Preferences", open the "Security" Panel

Select the "Security" Tab

Under the "General" Tab, select "Require password to wake this computer from sleep or screen saver" option