Problems with property managers and renters

[Alethea Sealy]

Hi. May I have your help? I have an investor. There are properties. I have been assigned to watch over the portfolio. I have hired property managers who have placed tenants. But I have high renter turnover. My investor is completely through the roof with anger and confusion on why the cash-flow is not coming like Niagara Falls. Note* We deal in the multifamily property market in Detroit, our average rent is $600. 

Sidenote: Where does one get training for this? I am a former 2nd grade English teacher, not comfortable with spreadsheets, cost analysis, getting property managers to save money on repairs etc. I do not know what to do with his demands and my job performance at 3 years in is horrible.