If you are using the Grade Centre and are using a Mac by default scrolling is turned off that allows you to move right to left through the columns. In fact the scroll bar is not visible at all.
You can turn this on by clicking on the logo in the top left of your Mac screen and from the menu that appears select System Preferences.
This will open the System Preferences menu. From the list of options click on the General icon.
Move down to the Show scroll bars section and select Always.
Once you have done this when you go back to the Grade Centre you will see that the scroll bar now appears.