How is it done ?

For regular play on most golf courses a greenkeeper will change the cups on the green to reflect a course set up of 6 easy, 6 medium difficulty, and 6 difficult positions on the greens. For tournament play the committee running the tournament will choose slightly more difficult pins than normal usually with input from the club pro. For professional tournaments positions are picked that reflect the amazing ability the pros have so a sadist will pick the positions.

Griller is response is mostly correct. Most private clubs & upscale, daily fee courses hand the players a pin sheet with that day is pin placements numbered. Each green is divided into five or six numbered sections & every day, the pin is placed in a location on each green within that area. For example, today might have been #1, so on every green, the pin would have been somewhere in the area corresponding to the #1 position on that green. The numbered areas r placed in a different spot on each green to avoid having all the pins in the front or back on a given day.

Most professional tournaments have traditional pin placements for each day of the tournament, especially well-known tournaments such as the Masters. For example, on Sunday at the Masters, the pin on #11 is near the lake, on #12 it is on the back right, on #13 it is front right, on #15 it is back left & on #16 it is down near the water so many shots will filter down close to the pin. These pin placements r known to all the players & allow them to play each hole strategically because the pins r always in the same place on Sundays.