Updating from iOS 5 to 6 will lose the YouTube icon. You can only get the original version back by downgrading back to iOS 5 but doing this will lose all the new functions available in the iOS 6 update. Problem This icon is missing on the Springboard (main icon menu) since you updated to… Continue reading YouTube icon missing on iPhone, iPads and iPods since iOS 6 Update
Using iPhone, iPad, or iPod with multiple computers
See Apple article HT1202.