preferred seat

[hoopla65]

How do I mark my preferred seat on merge?

[WhiteRider]

Please see the Tutorial: Preferred Seating which explains how to set up preferred seating and has pictures of how the seat numbers are arranged at each site.
IIRC to set your preferred seat in the Merge software you need to join a table and then click the "chair" icon near the chat box and option buttons (although the layout could vary at different skins).