USA passport can enter for 30 days. Want to stay longer?

Kyle, if you have valid entry permit to mainland PRC, then you can exit to mainland PRC and re-enter Macau to obtain another 30 days. But the time gap between your exit and re-entry shouldn’t be too short.
If you want to live there, you can find a job to work there or study there. In this way, you can get residence permit there and live there.