Saving Photoshop CC2015 PSD file for Older Version CS6

[RusticTrouble]

I have a file I am preparing to send to a printing company. I am using Photoshop CC 2015. I have saved the file as a PSD file. The printing company is using CS6 and are unable to open the file. They have asked me to save the PSD file for older versions. It still needs to be editable and have layers. How do I do this? I know I must be missing something simple. Any assistance would be awesome. Thank you in advance.

[Barb Binder · Accepted solution]

Edit > Preferences > File Handling (Windows) or Photoshop > Preferences > File Handling (Mac OS):

Set Maximize PSD and PSB File Compatibility to Always, the save the file again. (This provides backward compatibility.)