Casinos have the ability to control some aspects of slot machines, but they are subject to regulatory oversight and strict rules to ensure fairness and prevent manipulation. Here are some ways in which casinos can control slot machines:

1. Payout percentages: Casinos can adjust the payout percentage of slot machines, which determines how much money the machine will pay out over time. However, they are required to follow strict rules and regulations set by regulatory bodies to ensure fairness.

2. Denominations and payouts: Casinos can also set the denominations of the slot machines and the payouts for winning combinations. Again, they are required to follow regulations to ensure fairness and prevent manipulation.

3. Placement and marketing: Casinos can also control which slot machines are placed on the casino floor and how they are marketed to players. They may use tactics such as placing high-paying machines near the entrance or in high-traffic areas to attract players.

It's important to note that while casinos have some control over slot machines, they are still subject to regulatory oversight and must follow strict rules and regulations to ensure fairness. In addition, slot machines are designed to be random and unpredictable, so no one can predict when a machine will hit a jackpot or payout a big win.