Need a solution & javascript code for my website pages

hey, guys i already build my website just having some problem and for that need a solution. I have four pages of HTML file project every page links to another page and I already did that, I'll explain to you guys by giving you an example. For eg: **page A** contains 4 button (Question Paper) (Answer Paper) (Syllabus) (Important Questions), **page B** contains 6 buttons (Computer) (Automobile) (Mechanical) (Electrical) (Electronics) (Civil), **Page C** contains six buttons (First) (Second) (Third) (Fourth) (Fifth) (Sixth), and **Page D** contains list of files that fetching data from Firebase database. If I click on a **Page** A button(Question Paper) it would open **Page B** button(Computer) and after I click on **Page C** it would open button (First) and final **Page D** contains a list of pdf files it will appear. but the problem is whenever I click on **Page A** button (Answer Paper) click on **Page B** button (Automobile) then by clicking on **Page C** button (First) then **Page D** Display the same file from Question Paper-->Computer--First. Note-if you do this work for one Specific branch(Automobile) then I can do other branches on my own. guys, please help me. I need a proper javascript code and thanks in advance. ps- Screenshot 76 is Page A, Screenshot 77 is Page B, Screenshot 78 is Page C, Screenshot 79 is Page D.