I play only a single line. for me using 2 or 3 lines at the same is a waste of tickets.
What i do is only run rows that did not win anything last spin but has gotten me mixed results. Sometimes, w/ 40-60 tickets, i get a lot of clintz while only missing one or two "free tickets".
Symbols are totally randomized; that means each line is totally random and they have no relation to each other. Therefore playing all three is senseful, because it gets you out of that slotmachine faster and you can do something you actually can affect...
I like to play all three lines at once because I'd rather know that I wasted tickets than know that i missed getting a huge prize on the row i didnt pick.
It really depends on how the wheel itself is programmed.
Quite likely, it is pure random in each slot. If so, that means your odds of winning are set per ticket, using more lines at a spin is just saving you some clicks.
Since I have yet to detect any pattern in the wheels at all, I would say that this is a fair assumption.
Thus, doing 3 at a time saves you clicks, and avoids the psychological horror of having grand prize show up on a line you neglected to use.
I allways use 3 rows but this is so that 3 oscars can't appear in the rows i havent selected.
Its at the top of the fight screen as one of the options (it looks like a slot machine and should have a number next to it which is your tickets).
Its not on all the apps though.