Prong related....doesn't work as well anymore????

Hello,

I am seeing that the prong collar isn't working as well anymore. It does it's job normally, but when she is really eager about something/barking agressively I have now found it not as useful. (To give you an example, have you ever had your dog pull on the choke collar and not care when they were younger....thats almost how this is)

Exactly how do you size up a prong collar perfectly? I guess all this time I had one that was not too loose and not too tight, but is there a perfect way that might help?

Any tips/ideas might help. (just for your information walking/regular training is fine with this one)

Thanks,

Ryan