When I open iTunes on my computer (with Windows 10) iTunes doesn't recognize my iPhone (6s) so I can't sync them. Any suggestions? Thank you!

Try the following:

1. Open Control Panel > Device Manager
2. Plug in your device
3. Locate Universal Serial Bus Controllers > Apple Mobile Device USB Driver.
   It is also possible the device may show under Imaging Devices, Portable Devices or Other Devices or as an MTB USB Device.
4. Right-click and select Update Driver Software...
5. Click Browse my computer for driver software
6. Browse to C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers or
   C:\Program Files (x86)\Common Files\Apple\Mobile Device Support\Drivers
7. Click Let me pick from a list of device drivers on my computer
8. Click Apple Mobile Device USB Driver
9. Click Next, then Close and exit Device Manager

Or try iPhone, iPad, or iPod not recognized in iTunes for Windows - Apple Support

Failing that try a full tear down and rebuild of iTunes as set out in Troubleshooting issues with iTunes for Windows updates.

tt2

i've also tried those methods to no avail

i should have added that i don't see the Apple driver in my USB list in device manager

Do you see any activity in device manager when you connect the device?

tt2