Stableford: how to put a zero score on a hole, using the scorecard

If I understand you correctly you do not want to add the actual number of strokes for a hole if you did not score any points. E.g. 6 strokes on a par 3? If yes, when on green and the watch interface asks for number of strokes, press the minus sign on the display until it reads (-). This will render you zero points for the hole and zero strokes for statistics when looking at the scorecard. It will simply read "-" for that hole. If you want to keep the number of strokes recorded even if you did 6 strokes on a par 3, just press the plus sign instead and tick it up to 6. This will render zero points in your scorecard as well but your strokes will be counted with the total no of strokes for the round.

If you play stableford and want the points awarded to be calculated in the right way, it is important to; 
1) set the score method on the watch to stableford
2) Look at the slope for the course. Let's say you have HCP 15 and the slope of the course awards you 17 strokes. In the watch interface under handicap, select local HCP and enter 17 for this round.

by doing this the watch automatically assign the 17 extra strokes you get to the corresponding holes with index 1-17 on the course and the only thing you have to do on the course is to enter the amount of strokes per hole.

This can be seen on the watch interface when playing a hole. In the top part of the screen under PAR information, e.g. Hole 3 PAR 4 it will be a small dot underneath showing you that you have 1 extra stroke for this hole. Meaning if you make 5 strokes you'll be awarded 2 stableford points in the scorecard. If you make only 4 strokes, you'll get 3 points. Should you have two exra strokes on a hole, there will be 2 dots instead.

/Knubblo

Thank you very much /Knubblo for the very accurate answer. 

And if I may, any idea to switch from scorecard to watch during the game?

Br’s