I wish that the slot machine would include vertical results (I don't want to think how many times I have received 3 Oscars... vertically).
"I allways use 3 rows but this is so that 3 oscars can't appear in the rows i havent selected."
Pretty good reasoning.
If you use 3 rows, your winning ratio is 3:4 (75%), so you have the highest chance to win something.. as oppose to 1:4 (25%) with 1 row... unless the slot machine is fixed, using 3 rows is the way to go.
If I counted correctly, the odds of winning are more like 58% on three tickets and if the singular line had a 25% chance of winning. But you're correct about more lines giving better odds.