Haha ok.
When you generate a meme, on the image generator there is a button (bottom left) that says "Change Settings." You can hit that, and it will give you the chance to change the text (or other things) about the meme without having to delete and remake it.
But I'm afraid that once it's submitted, that's it (at least I'm pretty sure of that). I don't know how to make any changes within the meme after it's submitted. You can change the tags, or the title, before it's featured, but as far as I know you can't make changes to the meme itself. :)