What value should Auto-Green be set to?

The Auto-Green value runs from 300 to 900 ms in 5 ms steps. yew's own published value is 710. That is a starting point, not a rule: the right number depends on your jumpshot.

Set 710, take standstill shots in online MyCourt, and read the feedback. If shots come up early, raise the value. If they come up late, lower it. Move in small steps and stop when the majority of shots read green.

If nothing works, check the two required settings first — Shot Timing set to Shots and Layups, Shot Meter Off — then look at the jumpshot itself.

Source: yew2K mod menu; yew's published settings.