Hi @GiangLe2024,

It looks like Instructure is aware of the issue.  They just posted the following known issue:  [OPEN] Editing from the Pretty HTML Editor jumps t... - Instructure Community - 625484.  Please watch that issue page for updates and resolution.  Since this is a known issue and there is now a dedicated page for it, I'm going to mark this post as "solved", meaning your question has been answered (not that the issue itself is solved yet).

-Chris