Mark movie or program as seen/watched

Hi everyone, 

I've seen a few posts about this, but nothing that I can find a clear answer on. 

I would like to be able to see which programs and movies I've already seen from the main information tab, and it seems that the only option is to do this by adding it to the watchlist, and then creating a list of items to watch - or to make sure I rate everything. 

Are there any other workarounds or am I missing a feature? 

Thank you so much for your help.

Natasha