For Mac Users
Click the Apple icon at the top left of your screen.
Click System Preferences...
Click General icon.
Set Show scroll bars to Always and then refresh your Zentail web page.
For Chromebook Users
Go to chrome://flags
Find the setting called Overlay Scrollbars and set it to Disabled.
Relaunch chrome.
Note: relaunching Chrome will close and restart any Chrome browsers you have open.