Q: Continuity from previous back-up to new phone

HI.

Got my 91 yr old father iPhone 6 Plus..

Upgraded to 6s Plus so that, at need - not just when phone is plugged in - he can say "Hey, Siri, call 911," etc.

He's in another town, no Apple store, so I will set up his phone from his 2008(!) iMac where I backed up his 6.

I just need reminding of the start of the procedure.

When iTunes asks, "Set up as new phone?"

and whatever the other option says,

which do I choose to move his apps, settings, data to the new phone?

THANKS for any help. I'm getting to be ancient enough myself that I don't feel confident interpreting on-line references where people aren't addressing me directly.