MacBook confusion...

I have selected the same update five times and my app store is still telling me the update needs to be made. The update is labeled "Pro Video Formats 2.0.1" ... Also the icon for my garageband app is telling me it is paused and waiting to be downloaded (updated), the app store is telling me it has already (though I know it hasn't updated yet) and only gives me an open option. What can I do to fix this and what can I do to ensure that such glitches (or whatever they are) are minimally possible. Is there any software or security measures I can use to clean up and lock up my MacBook? I prefer products made by or highly recommend by Apple, Inc.

Help me please....

Trevor