You could be bound by significantly different rules without actively agreeing to them — just by continuing to use Yelp after a change.
Yelp's Terms significantly limit how users can resolve disputes — binding arbitration and a class action waiver mean most users cannot sue Yelp in court or join group lawsuits. Users also grant Yelp a broad, royalty-free license to use any content they post, including photos and reviews. You can opt out of the arbitration agreement by sending written notice to Yelp within 30 days of first accepting the Terms.