Is it necessary to rebuild stats after an update?
No, unless the update includes new stats.
I set up the font size and colour to my taste, now I wish to upgrade to the next limit. Do I need to tune the HUD/Popup again?
Why is HUD in the observer mode not displayed on PokerMaster?
It is impossible to run the Dynamic or Positional HUD in the observer mode, but you can run any static HUD like that.
May I get a refund if the HUD doesn’t suit me?
No, since there is an option of requesting a trial period or buying a monthly subscription.