Coach changing springs?

Hi!

I am almost 100 classes in and like to challenge myself and go heavy but it seems like sometimes when a coach changes my springs for me (like today we were doing dumbbell triceps while he changed springs), they make it really light! Is there a rhyme or reason to how they change the springs? He only gave me like two greys and a white and I saw other people with more greys or a black. It made me feel frustrated the rest of the class because I had to stop and change my springs and it made me feel like I didn’t look strong enough to handle harder springs or that he didn’t think I was capable :( Before we got to arms I was amplifying on other exercises beforehand.

I know it’s not the biggest deal! I just wanna know how they choose springs.

Thank you :)