Hello, gref1975
Thank you for visiting Apple Support Communities.
The best option would be to create separate user account on the computer that you separately use to sync with. This keeps contact and calendar data from being merged together. You can however still sync or share media with each user by following the steps in the second article below.
Do you share your computer with someone who has different tastes in music and media? You can create separate user accounts for each person who uses the computer. You can maintain separate, personalized iTunes libraries and customize each devices' sync settings accordingly.
Learn how to set up other user accounts.
Look in your computer's Help documentation to learn how to set up other user accounts. To find this information:
- Click the Start Menu and click Help or Help and Support.
- Enter "new user" in the Search field.
- Press Return.
If you create multiple user accounts on one computer but want the same media to be available in iTunes for all users, you can share music between different accounts on a single computer.
How to use multiple iPhone, iPad, or iPod devices with one computer
https://support.apple.com/kb/HT1495
iTunes: How to share music between different user accounts on a single computer
http://support.apple.com/kb/HT1203
Cheers,
Jason H.