On my return, I accidentally indicated that my parents could claim me as a dependent. Turns out they are not able to claim me. Do I need to amend? How will this affect my refund or any future economic stimulus payments?

It turns out that I made too much money this year for my parents to claim me as a dependent. When I did my return, I indicated that somebody else is able to claim me as a dependent. Will I need to file an amended return? Will this reduce or increase my refund? If there are any economic stimulus payments in the future, would this prevent me from claiming those?