I signed up, but there's no explanation after signup either. It doesn't seem private since I keep seeing other people's random posts, despite this being MY memory box.

We made Cove to help remember experiences and tell stories. Interests are chapters of our lives, like cooking, reading, and traveling.

I'd recommend putting that somewhere on the site. Right now there's no hint as to the site's purpose.

Personally, I need to see what I'm signing up for before I make an account for anything. You need to show us what it does!

thanks, we're working on showing the feed on the home page (before signing up)

Worst landing page ever. You can't "hack" conversion by refusing to tell people what they're signing up for.