What you need.
Firebug: [ Register or Signin to view external links. ]

Firefox: [ Register or Signin to view external links. ]

1.Download them then go to your youtube then go to themes and Colours.

[ Register or Signin to view external links. ]

2. once opened should look like this.
[ Register or Signin to view external links. ]
If not click the drop down arrow next to the <selcet

3.Right click then go onto inspect element Once done that should look like this.
[ Register or Signin to view external links. ]

4.Click on Times new roman then you need to make it this.
Arial Bold And Arial Bold
[ Register or Signin to view external links. ]

5.It should now have Arial Bold on the drop down arrow on font like this.
[ Register or Signin to view external links. ]

6. Save it and if you followed this it will look like this.
[ Register or Signin to view external links. ]

Thanks for reading.