Hey, thanks for the report. This is a known issue, model preferences sometimes reset after updates. The team is aware, there have been a few fixes already, but the bug can still come back from time to time.
Similar reports from other users: Model reverts to composer-2-fast on each new chat.
For now, the only workaround is to manually check the selected model after each update. I know it gets in the way, especially given the cost difference between Composer 2 and Composer 2 Fast.
I’ve added your report for prioritization. Let me know if there’s anything else.