Will "set up new iPhone" in iTunes wipe my swapped iPhone? I just upgraded to iPhone 6se at a Sprint store yesterday.  They moved all my data from old phone to new at the store.  Now, when I plug my iPhone into iTunes (v12.5.3.17) on my macbook, it only presents me with options to "set up new iphone" or "restore from backup."  All the backups are old.  If I choose "set up new iphone," will it wipe my device?  I'd prefer not to lose everything I have on my iphone.  Will my iPhone ever be synced to my iTunes again?
No, it won't erase anything.

Allow me to translate that dialog  to idiomatic English:

"I don't know anything about that iPhone you just plugged in.   You have two choices:

Erase it, and then restore it from the back up (of some previous iOS device)?
 Or
Treat it as a new iPhone that iTunes will now keep track of?"

Does that help?