G80 setting up slope index for whs handicap

G80 setting up slope index for handicap. Does anyone know how to do this. I select my course, and then select the scorecard and then the slope index option. I enter in my handicap index and it prompts me to select a tee, then all it does is sit there and doesn’t allow me to enter in the slope index. I have used the “other option” show and it allows me to put in both handicap index and slope but says I’m a 8 handicap. Which I’m definitely not. Any advise would be gratefully received. Cheers