Does sync always sync everything?

[healer]

When I select Photos in iTunes and then do a sync, I expect the synchronization only applies to Photos only. However I always receive the following message. Does it mean it actually synchronize everything, not just the photos I select?

The message to the effect of the following:
Some of the purchased items on the iPad could not be transferred to your iTunes library because you are not authorized for them on this computer. Would you like to authorize this computer for items purchased from the iTunes Store?

 

[scifan57]

When I select Photos in iTunes and then do a sync, I expect the synchronization only applies to Photos only. However I always receive the following message. Does it mean it actually synchronize everything, not just the photos I select?

The message to the effect of the following:
Some of the purchased items on the iPad could not be transferred to your iTunes library because you are not authorized for them on this computer. Would you like to authorize this computer for items purchased from the iTunes Store?

Are you trying to sync with a computer that hasn't been used for that purpose before? As the message says, you have to authorize the computer before you can sync.

 

[healer]

I don't think I have done a backup. However, I have synced the photos many times before. Every time when I want to change the photos in the iPad I select photos and do the sync.

The message I get every time is what I mentioned in the previous post.

 

[ajcgn]

I believe that when you sync with iTunes you can check a box to indicate if you want to sink apps as well. Hopefully by un checking the box you will get rid of the error message.

 

[healer]

Upon receipt of your response, I've just checked the following.

The Sync Apps hasn't checked anyway.

When I uncheck the Sync Movies, a message pops up saying all existing movies on the iPad will be removed. It gives an option of "Don't Sync Movies". I am not too sure what it means. If I choose "Don't Sync Moves" instead of checking Sync Movies, does it mean it would leave the movies in the iPad untouched?

Lastly, I wonder if it matters what screen whether the Photos or APPs is on when I click on the Sync button. All the time I have supposed it only syncs the area that I have the screen on when I click on the Sync button. In other words, I expect it to sync the Photos only if I click the Sync button when I have the Photos screen on.