When playing the multi line, multi coin slots...always always always cover all the lines...so if it is a penny machine, and has 30 lines, hit the 30 button and then on the bottom row, you will have how many coins in that you want to play per line.
Hit 1 and your bet is .30 and so on.
Nothing worse than hitting the 1 and 1 button for one penny and hitting a jackpot. Your only covering one line on the machine, and you want to cover them all. Not necessary to play the max which is the most lines on top and the most lines on the bottom but VERY IMPORTANT TO COVER ALL LINES.
I had to spread this knowledge as a very wise man taught me how to play smart. Good luck and have fun and remember when you win...two important words CASH OUT