It's quite common that the support service recommends after making any changes in the system to clear the cache in the browser or reload the page. And if to refresh the page will be enough to press "F5" or "Fn + F5", then to clear the cache in each browser has its own peculiarities.
If you need to reload the page with a cache cleanup, use the "Ctrl+F5" combination (for Windows).
If you need to refresh the cache cleanup page on your phone - just open it in incognito mode.
Links to official pages on how to completely clear the cache in all popular browsers:
Google Chrome - https://support.google.com/accounts/answer/32050?co=GENIE.Platform%3DDesktop&hl=en
Mozilla Firefox - https://support.mozilla.org/en-US/kb/how-clear-firefox-cache;
Opera - https://help.opera.com/en/latest/security-and-privacy/#clearPrivateData
Safari - https://help.apple.com/safari/mac/9.0/?lang=en#/sfri20948
Microsoft Edge - https://support.microsoft.com/en/help/4027947/microsoft-edge-delete-cookies
The combination "Ctrl+Shift+Del" to quickly open the browser settings works for the above browsers except Safari. For this browser use the combination " + R".