Garmin / Zwift / WattBike

I did a Zwift session on a wattbike at my local gmy this morning, and also captured it on my Garmin Fenix 6. When I completed it the difference in distance was considerable (roughly 10km) so assume its something to do with wheel size setting - is there anywhere in the Zwift software I can find this ?

Ignore the speed and distance that the Garmin is reporting, it does not know about the Zwift variables.

This could help you in understanding it a little more: How Does Zwift Determine My Speed?