Arm size?

This is my first time posting so please go easy on me :') I've been working out for almost 2ish years and granted that I've seen growth in my arms, it's not as volumous(?) as I want it to be. the reason I'm her eis cause my chest has seen growth and so has my back and every other part except my arms and shoulders my question is how to get mass to go there instead of my belly lmao. am I just not training hard enough?

any advice is insanely appreciated, thank you :)