Clearing the cache on your phone can clear up many issues.

If you are using Internet browser that is stock with your Samsung phone, the controls are in a different place.
Instead of the TOP RIGHT it is the LOWER LEFT.


Lets clear your Browser Cache and see if your problem goes away.
Here are the screen shots to direct you.



Click on the 3 lines in the Lower Right
 

Then Select Settings

Then Privacy and Security


Then Click on Delete browsing data


Then Select Cookies and Site Data then Delete


Wait for the data to clear then click the arrow in the Upper Left 2x.

This will bring you back to your browser so you can login again.