Internet Explorer 8 Video :
How To Reset All Zones' Security Level

Step #1: Click on Tools in the top menu bar.
Step #2: Click Internet Options.
Step #3: Click Security tab.
Step #4: Click Reset all zones to default level.
Step #5: Click OK.

Result: All internet zones were reset to their respective default security levels.

This action is a convenient way to reset security settings in all zones back to default. This is useful to do when security settings have been changed with undesirable results and it is difficult to find the exact setting that is causing the problem.