Single question page

Each particular question page shows other sets of Q&A.
Please see 2 following screenshots.
Red Circle Question page shows another set of Q&A.(It isn’t Red Circle Question.)

・Is this specification or bug?
・Please tell me solution.
・If solution is the program code, please tell me solution outline (code to use, file name to edit etc).

I’m a WP & program begginer, plesase cooperate.
Thank you.

All questions page (Red = selected question)

Particular question page (Red = selected the set of Q&A, Blue = anoter set of Q&A)