show more pages on membership access levels

When using Memebership I am trying to set the positive/negative rules but it only shows 50 pages. I need to be able to see /access more pages so I can add them to the positive list.

If I go to Membership > Access Levels > Edit A Level > Drag the list of pages to positive rules

At the bottom it says "only the 50 most recent pages are shown". I have more than 50 pages so how do I fix this?

Or is there another way to set access to certain pages.

Thanks.