Automatic partial formatting of text between certain values

I'm hoping someone can help me out further with this.

I've managed to locate some code that will bold text between brackets.
And I've also managed to change the Excel code so that the text between the said brackets is red.

What I am wanting to achieve is for Excel to automatically format partial text between double angled brackets.
When I change the "(" or ")" to "<<" and ">>" it no longer works.

I'm very appreciative if anyone has any tips or advice!
(PS. I'm very new to the VBA side of things, in case you couldn't already tell! :P )