I am 58 years old and I just received SSI if for some reason the only amount of money that I'm getting is $850 a month I cannot pay rent without going into hole every month and I don't understand why am I getting just no amount of money from SSI
Supplemental Security Income (SSI) is a needs based program administered by Social Security. It is a federal program designed to provide a minimum level of income to people who have little or no means of self-support. The maximum federal SSI benefit in 2019 is $771, so if you're receiving more than that it's probably because the state in which you live has a supplement program to provide assistance in addition to the federal program.
It sounds like you're probably already receiving the maximum possible amount of assistance, but you could always double check with Social Security and the agency that administers your state supplement program.