Originally Posted by Mr Cheeks

ok i'm not a FCP expert but its actually fairly easy:

to make your title be the same length as your clip, if it's already on the timeline, double click on it and load it to the viewer window. there make sure that the length is about the same as the clip that you want to watermark. if not key in a numerical value for the length on the upper left box in the viewer window, press enter to accept the value then drag the right side of the watermark on the timeline to stretch it and match the length of your clip.

to move the watermark around, make sure it's loaded on the viewer window again then chose the Motion tab. then click on the + sign next to the Center option when the red plus sign shows up on the Canvas window, click on it but do not release the mouse button until you're done moving it around to where you want, then let go of the mouse. repeat that last step until satisfied.

to save the watermark for future use. create a dummy project call it something like Presets (do not close your last project, leave it open). from the timeline drag and drop the watermark to the browser window (usually on the upper left with standard window setup) of the newly created project and voila. your watermark has been saved as a preset. with drop shadows and all.