If I go into my Philadelpjia Phillies collection, select Sets, and select 1979 Topps, I see this:
At the drop dowm, I can select whichever collection I want to update.
If you're not seeing this, contact Admin. Give him the URL of the page you're trying to access. I do not experience what you're describing.
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 3/4/2024). I have added a large portion of my inventory to the site, and currently have trading turned on (details are in my profile).