All my routes are in Miles however they are always shared in FB in KM's only.

Hey @RZ27_2 ,

Thats a great question. You can adjust the Units of Measurements for your profile within your settings.
Here is our support link that reviews how to do so: https://support.strava.com/hc/en-us/articles/360057378851-Changing-the-Units-of-Measurement-on-your-Strava-Account

I hope this answers your question and thats for asking in the community!

All of my settings are correct for miles but when sharing to FB it displays KMs

Hey @RZ27_2,

Thank you for verifying, Please submit a support ticket and we’ll be happy to investigate further.