The "Set Dealer Buttons" dialog changed a little in version 3.2 and can be confusing to some. For most dialog windows, the idea is to make the changes you want and then confirm them by pressing the OK button, at which time the changes are made. In version 3.1 and earlier, the "Set Dealer Buttons" dialog was just a few selections (set at seat 1 or set randomly, and "must have player seated" checkbox). Select the appropriate options and press OK, at which time the dealer buttons are set.
What I didn't like about this is it didn't provide any preview, or the ability to manually set any dealer button, or the ability to adjust the random selections before they are "committed". Of course, changes could always be made on the Tables tab after the dealer buttons were set, but those changes are visible to your players. What I wanted was a way to set the dealer buttons (randomly, manually, etc), make adjustments, and commit the changes all at once, without the steps taken being visible to your players. So the dialog was changed in 3.2 to show your tables, allow you to randomly set the buttons, then make changes, all before you press the "OK" button to commit the changes to the tournament. Players no longer see any in-between steps.
So the dialog now works like most other dialogs: make changes, then when you're done either "Cancel" and abort those changes, or "OK" and commit them to the tournament.
All this was to say, you have to press the "Go" button to have the dialog set the dealer buttons. When you're satisfied with where the buttons are located, press the "OK" button to commit.