If you know you'll be changing the durtation of titles in future projects, you'll have to stop using the Title Designer to set the fade-in/fade-out.

Instead, modify all the text boxes in your template project to use regular fade transitions placed at the start and end of each title on the timeline. You'll also need to set the In and Out Animations for each clip to No Effect to avoid the current headache.

When you work with that template in a new project, you can simply drag the end of the title (or select it and click on the clock icon to type in the duration) without affecting any of the fades.

I'm not sure what you mean by "motion keyframes" though. Have you manually keyframed the text to move across the screen? If it's an automated effect, that should be automatically adjusted when the title is shortened. If that's not what you're seeing, please provide some more details as to the type of movement preset (or motion keyframes) you're using.

Thank you for the advice, that seems relatively straightforward. I will take a look at it.

As for the motion keyframes, I guess they're technically called Position keyframes. I was confusing them with the Motion tab (Object/Animation/Motion on the left). For example, I have two titles slide in from the side, then fade out. If I shorten them up, all the Position keyframes are lost. I presume it's a similar problem to the Opacity situation.

One way to deal with position keyframes is to add a bunch of keyframes in the middle ahead of time, like maybe every second.

Then if you shorten the title later on, PD will have a better idea of how to continue the motion since each of the new keyframes will inherit the current position value at its location. You still might need to make a final tweak, though.