When I log on to some of my routers such as my Centurylink Actiontec Q1000 I get log in prompt but no graphics. So on this one I dont even see Apply button. Does this on some routers. Seems to happen only on newer routers. Older ones work fine. Happens with Google Chrome, IE11 and Firefox. I have other Windows 7 PC's that have no issue's. I only access routers from LAN/Intranet
Look for blocking software of any kind on your browsers and disable it to see if that will get the images you need to see on your router pages.
I had the same problem in Firefox with Ghostery and AdblockPlus on tight settings. All I could see on our router's login was solid black. Switched over to a fully wide open version of Firefox and could then see the login and other necessary fields.
That could be why you have problems on some PCs but not on other ones.