The default version of the "Trailer" Title should be located in the Credits category. (I believe it was originally developed for iMovie, but "appeared" somewhere along the line in FCPX.) If you made an alternative version in Motion, then your version would be automatically renamed "Trailer copy" (unless you gave the edited version a custom name.)
This title can be something of a nightmare to deal with... mixing fonts and sizes like that, trying to keep line spacing "straight", etc., so...
If this is something you need to use rather often, then I would like to submit, as a suggestion, this alternative:
https://youtu.be/wOSjtqGhB2A
It's main feature is each piece of text is its own "object" and labels (like executive producer) can be "stacked" - formatting is as simple as dragging the text - all lines are "auto-aligned" to the center - you cannot mess up the line spacing - and there is an accessory font containing MPAA Ratings tags and parts (including laurels and Closed Caption icons [*Use responsibly*]).
HTH