How can I set a new app as my default launcher on a Galaxy Ace? I downloaded a launcher app on my Samsung Galaxy Ace (iPhone Locker; actually its a locker app but it pretends to be a launcher). Now when I press the Home button, the list of launcher apps pops up. This list contains iPhone locker, and when I select that it is set, but the next time I click on Home the launcher list pops up again. I checked in my application settings and iPhone Locker's Clear Default button is grayed out, so it looks like it has not yet been made the default app. How can I make this my default launcher?
Go to menu > settings > applications > manage applications > your current launcher and tap Clear data button. Then, after pressing "home" button, a dialog should pop out, asking you, which application should be used to complete the task.

If this won't work try reinstalling the application. And do not move it to SD card ;-)