Steps to stop Firefox from opening multiple tabs:

• Select Settings from the menu button.
• Navigate to the Tabs area of the General panel.
• Ctrl+Tab cycles across tabs in the order they were last used: If you wish to use the Ctrl + Tab keyboard shortcut to switch between open tabs in the order you viewed them rather than the order they show in the Firefox window, select this option.
• Deselect this setting if you wish to use Ctrl + Tab to move to the next tab and Ctrl + Shift + Tab to switch to the previous tab.

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