Well, that is why you keep some things to yourself, isn't it? This stuff is actually hard to copyright, per the US Patent Office, not the other way around.
My rule of thumb is if you haven't made it, don't post it but you can post a link to it and talk about it.
If you have made a recipe, feel free to tell us how you made it and what you used to make it, and use the name of the recipe to tell us what it is. For instance "Buffalo Wings with Blue Cheese Dipping Sauce". As you can see, straight to the point not claiming it as yours just posting what you made.
As for changing it around, depends on how much. If you can see it came from another source and has just been tweaked to your personal taste, then just say so. Don't take credit as if you invented the recipe, that is all. For instance, "This is my take on a recipe posted by BAM called XXX. I changed the following and this is what I did."
If you have played with it and changed it so much you can barely tell what it started out as, then that is all yours name it and post it as your unique recipe. For instance, "this is Mav's DO Easy Meat n Beans".
Of all the recipes I posted, some were made up, and some were where I read 3 or 4 of the same type to get an idea of what is common, then I put together what I wanted that was common, then I figured out how I would cook it. So that pretty much makes it my version. Nearly every recipe has been made before, so it’s hard to be completely original these days!