Setting Crank Length


Need some help here. I have recently purchased a Favero Assioma power pedals. My actual crank length at 170mm which I have set in the Assioma App. However, everytime it will be defaulted back to 172.5mm after I have connected it to Zwift no matter how many times I changed it. And there’s no way to set crank length in Zwift. I don’t have any cycling computer, only use the power pedals for Zwift.

Any advice will be greatly appreciated.