Delete and reinstall the app

Some apps can become corrupted because of malware or because of file tampering. If you’re unable to resolve the problem using either of the above methods, you may want to try reinstalling the app to give it a fresh start. To delete an app, simply drag it to the Trash.

For Mac App Store apps, launch Mission Control with a four-finger pinch, click and hold on the app until you enter ‘jiggle’ mode, and then click on the “x” button to delete the app. Afterwards, reinstall the software by re-downloading it from its website or the Mac App Store.