In-Game Assignment
You can adjust controller assignments anytime during game play, and while you change the assignment, offline games will pause. If you're playing online, then the game will continue but you won't be able to see anything. To change your controller assignment, press and hold the "PS" button until a menu appears on the screen. Select the "Controller Settings" option and select "Reassign the Controller." You can now adjust the controller number up and down and then press the "X" button when you're done. If you selected a controller number that someone else had, then you'll switch numbers with them; the effect will be the same as if you'd traded your controller for that person's controller.
XMB Menu
You can also change your controller assignment in the XMB menu. Just navigate to the "Settings" section and select "Accessory Settings," then "Reassign Controllers." This works just like assigning a controller from the "Controller Settings" option during a game; you can increase and decrease the controller number and then press the "X" button when you've selected what you want. If you select another controller's number, you'll swap numbers with that controller.
LED Status
You can easily find out what number your controller is by looking at the LEDs on the top of your gamepad. Both Sixaxis and DualShock 3 controllers have four LEDs to indicate their numbers; the numerals one through four are by each LED. If you connect more than four controllers to your PS3, two of the LEDs will light up to indicate numbers five, six and seven. You cannot connect more than seven controllers to a single PS3.
Other Settings
The PS3 also lets you change the settings for how long your controller waits before turning off and for enabling or disabling the DualShock 3 vibration. To change the "auto-off" option, navigate to the "Settings" section of the XMB menu and select "Power Save Settings," then "Controller Auto-Off." You can choose 10 minutes, 20 minutes, 30 minutes or never. To enable or disable the rumble feature in DualShock 3 gamepads, go to the "Settings" section and select "Accessory Settings," then "Controller Vibration Function." You can also turn this feature on or off during a game by pressing the "PS" button and selecting "Controller Settings."