Where the hell is the model selection button on the mobile site ??

You can select the model you want BEFORE your conversation start, but once it's started the selection button disappear, where is it ??

https://preview.redd.it/6m973gpcgulg1.png?width=1125&format=png&auto=webp&s=cdec7b15bda5738aa01a9215f9dd9c5c4a3fbb45