My grandmother has dementia and my uncle and his wife got POA over her but they live in Florida she lives in Georgia. Any advice?

Power of Attorney is NOT LEGAL GUARDIANSHIP. It’s a document that allows you to designate someone else to handle certain affairs for you or to make decisions on your behalf when you become incapacitated. And it does not obligate or require the POA to take care you. Neither a POA or guardian have to provide 24/7 care. A legal guardian has more responsibility but can oversee and delegate care rather than provide hands on care.

You don't have POA over someone, someone assigns you. Its a tool. Grandmom would have had to assign Uncle before her Dementia. She has to be competent to sign paperwork.

Guardianship is different. Your Uncle would have applied to the courts for this. A judge would have OKd it based on info Uncle presented saying grandmom because of Dementia could no longer take care of herself. Uncle is going to have to report to the State how grandmoms money is spent. He is going to have to report how she is doing and make sure she sees a doctor regularly. He can put someone in charge of her care but he has to be on top of it.

Are you caring for Grandmom?

POA is not legal guardianship. It is either for health decisions or for financial work and the person is appointed by your grandmother. She alone can appoint someone else, and she can do this only if she is legally competent mentally to do this. The medical POA is to make decisions when your grandma cannot in a manner consistent with what her expressed wishes were, or in her best interest. POA for financial pays bills, takes in assets, keeps records of all that and all accounts, sees to taxes if grandmother cannot, and etc. It is not necessary for either to live in same town but it sure would be helpful. I was one half a State away from my brother and that made it more difficult. It is no easy job. You should look up the duties, and the differences between POA, DPOA, Guardianship, conservatorship and representative payee (necessary to change around any accounts where Social Security is concerned. That will give you a world of information.
What problems are you encountering? Do you live with or near your grandmother? Has she mentioned concerns? Your Uncles is, I assume, your Grandmother's son? He would be the natural one to appoint in this if he is competent to do this.

POA is the ability to make decisions in her best interest, not a contract to provide hands on care. They can set up home care, or other living settings for her, as long as she is taken care of.