Swap Data Between Two iPhones

Another option would be to back up each device to iCloud. If you each have a unique iCloud ID, then once you backed up your device, you would then:

Go to Settings>General>Reset>Erase All Content & Settings

Swap the erased phones, and then set them up - sign into your own iCloud account

When you get to the part about setting the iPhone up as a new device or from a backup, choose restore from iCloud backup

Select the backup you did just prior to erasing the other device to restore the new one with

The backup itself does not take a super long time, but the apps and media have to re-download, so that can take awhile. Just be patient. It's a good idea to plug the devices into a power source when doing the restore, and keep it plugged in until all of the media has successfully downloaded.

If you are each using the same iCloud ID, then post back and we can discuss alternatives.

Cheers,

GB

I strongly suggest you re-think the bounds of the requirements:

Kiplop wrote:

... using only one Macbook and one iTunes account?

Using only one MacBook is just fine, but you should absolutely use more than one iTunes account (which can be done on the same Mac - just set up multiple users on one Mac).

Be certain you each have your own unique Apple ID and password. Then proceed as follows:

• Start by being certain you have the current iTunes (12.5.5) loaded on your Mac.
• Each of you log in to your username/password on the MacBook. These can, of course, be done separately.
• Each of you back up your current iPhone using iTunes in your own, individual account.
• Each of you prepare your iPhone to give away per these directions: What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support
• Now exchange iPhones. Each of you will receive an iPhone that is completely erased, software-wise just as if you took it out of the box.
• Each of you then use your iTunes version in your own individual account to set up your "new" iPhone, each with your own, unique Apple ID.
• Of course, at some point, you will have to inform your cellular carrier of the new ownership and change in telephone numbers. I assume with all these steps that you are both using the same cellular carrier.