@justforthelulz No worries, you are not the only one who mixed it up.
As for who calls him what:
-Tsurumi Rie and her father Tomio, as well as Tanaka and all his teachers always call him Kamenashi
-The Stuco President and his other friends always call him Kanenashi
-Akanishi is a bit special as he tends to switch depending on the context and who he's talking to (but yes he usually says Kanenashi)
I feel like I should properly clarify it in an end card one of these chapters... Along with the interesting bit of trivia I just stated above. Cause y'know, not everyone reads the comments.