Ha, they don't make it easy.
You can go to the Your Account & Lists tab, in black bar, upper right and then select
Your Music Library, (it may have you sign in again) and then on the left side panel, near the bottom,
choose Amazon Music Store.
There may be other ways as well. (And maybe something in the e-mail they send announcing your credit.)
Promote your business here - Businesses get highlighted throughout the site and you can add a deal.
I have been choosing a slower shipping speed for the $1 digital credits but don’t know how to find eligible songs or videos I can redeem the credits on. Can anyone help?