Shop Username Question (another Stupid Question)

I changed my username a while ago, and before buying goods from the store I'd like to know which user I use during the purchace process; The old one, or my current?

And also, since my forum account hasn't updated my new username, will i miss out on the new tag from upgrading?

And yes I am aware of how stupid these qustions are, but I'd like to be sure before I screw myself over $30 on a rankup and crates because I failed to check what I should and shouldn't do. No harm to check, right?

 

your new username
no u wont lose anything