Of these choices, which are the best names for a frozen yogurt shop?

Start over: Your use of an already registered trademark in your name is going to be a problem. Here is a partial list from the USPTO Trademarks Registration and Applications database... there could be hundreds of others already in use or registered in one or more state databases as well:

http://tsdr.uspto.gov/#caseNumber=73100830&caseTyp... FRO-YO frozen yogurt confections and mixtures

http://tsdr.uspto.gov/#caseNumber=77537746&caseTyp... Fro-Yo Fresh frozen yogurt

http://tsdr.uspto.gov/#caseNumber=85250818&caseTyp... Fro-Yo Frenzy frozen yogurt

http://tsdr.uspto.gov/#caseNumber=85616740&caseTyp... Fro-Yo Mashups frozen yogurt

http://tsdr.uspto.gov/#caseNumber=85673494&caseTyp... Fro-YO self-serve frozen yogurt

http://tsdr.uspto.gov/#caseNumber=85944579&caseTyp... Fro-Yo dessert shop

http://tsdr.uspto.gov/#caseNumber=77555208&caseTyp... Fro Yo Love yogurt shops

http://tsdr.uspto.gov/#caseNumber=85408035&caseTyp... Fro Yo Spot yogurt shops

Fro-Yo Fever! It sounds like something everyone can say when they feel a little guilty for constantly going. Example...

Me: Mom can we go get some frozen yogurt?

Mom: We just went yesterday, and the day before that! Aren't you sick of the stuff yet?

Me: If I'm sick, then I have the "Fro-Yo Fever".

Bum dum tss...I'll let myself out now.

Fro-Yo Fun

sorry to do this to you mate but I like Fro-Yo Falls I sort of think falls-waterfall-liquid-milk-dairy, just for association reasons.

I think Fro-Yo Fever sounds the best, it seems to roll off the tongue, second choice would be Fro-yo Fun.