New boater with '98 evinrude shifting problems

[Willie1280]

So I just bought a used boat with a 1998 e150elecd 150hp 2 stroke motor on it. It fired up and ran and shifted like a champ in driveway with the muffs. Took it to the launch for the maiden voyage of course with dozens of people around. Push off the dock and go to put her in reverse and I get grinding. Made my way back to dock, pulled cover and then sit cover that's over the cable adjustment screws. After a half hour of guesstimating and tinkering with both adjuster wheels I got it to work. It seemed to run well but reverse seemed like she could go faster but I was out of throw on shifter.

Is there a rule do thumb for setting theses 2 screws?
I can't find any manuals online for this motor.

Thanks in advance!