Reported by @dense kelp
Scroll down to memory and click on the underlined 'saved memory'
Then ontop it'll say revert back to legacy experience and click it Interact normally with ChatGPT (send messages, idle briefly, etc.) Or refresh the browser.
After a few minutes, observe the memory option automatically revert to the new memory summary.
The selected memory option (legacy saved memory) should remain consistently active, regardless of the amount of time or activity within the chat session, until explicitly changed by the user.
The memory option automatically resets and switches back to the new memory summary periodically after interaction or a few minutes of inactivity, disregarding user preference for legacy saved memory.
CHATGPT Web browser and App.