You can not apply speed adjustments to title clips but there are a few things you can do to alter them. Maybe not what you're after but give it a try
Trim or extend the title by dragging the yellow handles - From some titles, this will make them animate faster or slower
Place the playhead (blue line) just past where the title animate on-screen, split the title using the scissors. You lose the animation but this allows you to have the title on screen as long as you want without animating off. You can apply a transition to the title to fade on/off-screen if you want.
Please add a request here if you would like additional control over titles