You can do that by updating the picture on your PDGA player profile, which will show on the leaderboards and scorecard graphics on PDGA Live, in just a few steps:
Your PDGA Player Rating is a number that shows how close your average round scores are compared to the course rating, called the Scratch Scoring Averages (SSA), of the courses you’ve played in competition. Players who average the SSA on courses played will have a rating of 1000 and are considered “scratch players”. A player who averages scores lower than SSAs on course they’ve played will have a rating over 1000.