Having worked over 12 years in the casino biz, I will offer the cold, hard truth. Slot machines are run by RNG's (random number generators). I will not go into detail about how the RNG works, just that slot machines are random. There is no way to predict if the next spin will be a winner or a loser. Even the casino doesn't know. In the long run the casino will come out ahead. I promise you that. But in the short term the player can and often does win. There is no skill involved in playing a slot machine. You can't outguess the computer. In your example, you got lucky in the short term. You played for 2 hours and won. Then you lost it back. The machine was not set to max out at $38. You could have won the top jackpot. Switching machines wouldn't have changed your expected result either. There are hundreds of slot "strategies" out there. But I can assure you none of them work. There is no way to overcome the house edge in the long run. You can, however, limit your losses by playing higher payback machines...and playing enough coins to cover all the paylines (on multi-line games). If there was a way to predict slot payouts, I wouldn't have had such a good paying job for so long!