Generally on a propane appliance it is correct there is no "Fuel Adjustment Screw" Like there is on a gasoline carburetor.
What there is an air adjustment slider This is OFTEN (But not always) a window in the large tube past the oriface with a slider over it.. If you are running rich you slightly loosen the screw open the window a bit more (Then tighten the screw) if running lean you Same procedure but close it a bit.. Slide it open/closed till you get the best flame.. If you do not know how seek professional help.
I grew up with propane so have done several adjustments over the decades.
