u/Available-Kiwi6357

Hey everyone, I’m trying to figure out how to change the fan speed from my thermostat. I just put in a new thermostat to try and fix the fan speed. Everytime I turn it on no matter what speed low,med,high it all blows at the same speed. I checked the wiring and all the codes (ChatGP) so I’m not sure how reliable it is but I just can’t seem to figure it out. From what I read they said it could be something to do with the unit in the attic only having one speed. The first pic is the type of thermostat. The second is how I wired it. The third is the old thermostat wiring. If someone can help me I’d greatly appreciate it.