There are two settings in Preferences

If you go to Open in (here open links in)

This will effect what happens when you click on a Fast Dial Cell, that is how it will open.
You can change to open in Current Tab.

The other setting here described as "show Fast Dial in Blank Tabs, effects the behaviour of Fast Dial itself.
So if selected CTRL-T will open Fast Dial for example.

So I think perhaps you want the first setting.

Many thanks