Hi there to change it back just press on your account in the corner and select mobile version, it should be just above the log out version
If you are stuck on desktop mode when reading then check the top of the chapter for a tab that says "New Version" it should be next to where it says latest updates
Hope this helps
@nnh_vu @Rue
Thank you to everyone who responded. I'm sorry if the situation was difficult to understand. I had prepared screenshots, but I couldn't post them, so I couldn't explain it well. Miraculously, someone understood the situation, and the problem was solved.
I'm truly grateful to everyone who reached out to me.

I'm sorry, but I don't know where to ask a question about the site's UI, so I'm writing here.
I'd like to know how to change the chapter screen display back to the mobile version.
I use this site on my phone. When I opened a manga chapter, I think I accidentally tapped a checkbox in the chapter setting UI and it switched to the desktop version display, but I can't find a checkbox to switch back to the mobile version.
Of course, the display settings of my web browser itself are set for mobile.
If anyone knows how to solve this, could you please let me know?