linking files working on one computer but not any other

does anyone know why certain editing will work on one of my computers, but when i try the SAME EXACT thing on another computer, it will NOT work?

the issue i have is when im in “edit page”. i conatantly upload files and link them in my “edit page”. the steps i take are:

1- media- add new- then upload a file. then i copy the file URL
2- i goto “pages” and select my page
3- i type in a description, highlight the description then click “link” at top of page
4- i paste the file URL
the problem comes when i click the “update”. on one computer, the page updates and it links and everything does just as i want it.

on any other computer, after i click update, while still in “edit page”- everything in the page becomes highlighted and nothing changes on my website.

any help would be appreciated