- The settings page has changed a bit and the SIM related options are under the name of the network operator
- You can now see chat settings under the operator messaging settings
- You can choose to use chat, disable or enable read receipts and download files automatically
But surprisingly the chat settings are not available on my other devices even after messaging update. So, may be it is sme kind of bug or A/B testing again. The device in question is Lumia 640 XL. The app version is 1.10.28004.0.