Hi Jennifer -
That probably means that on the computer where you don't see them - you're not logged in. If you're not logged in the site doesn't know you're "you" so it can't let you edit posts
And as far as your gallery goes - it depends on what galleries your cards are in. Most of our galleries are visible to logged out users, but some we save for registered members. Membership has its priveleges!
So if many of your cards are in those galleries, they will not be visible to logged out users. Your member gallery is, however.