The How To Use link I was referring to is the top right one, the page I get into if I click it it's this one:
https://www.salesforce.com/solutions/small-business-solutions/help-desk-software/?mc=desk

Yes, and i have the same problem on opera too

Sure, I've attached a screen of the tabs before clicking on "Customizations" and after clicking on that tab, the tab Customizations just disappears

Hi, I use Chrome