While a shot is being tracked on the Apple Watch, the lapsed distance can be seen in orange on the bottom of the Apple Watch UI in addition to the club that shot is being tracked against.
Right before, or even after you hit your ball, you can adjust the club that is being tracked by turning the Digital Crown. This can only be adjusted if you have Club Recommendations turned on for the round. Only Pro and Champions members have access to the Club Recommendations feature.
Once you proceed to your ball, you will automatically lock in the Club that is being tracked. The Club Icon will change from Orange to White, indicating that you can no longer update the shot that is currently being tracked.
Shots can always be viewed or edited during or after a round by accessing the in round Menu> Tracked Shots, or after your round, you can locate tracked shots in the Rounds Section of Golfshot; just select a round, then select Tracked Shots.