This link reveals all the basics:
https://www.kenstone.net/fcp_homepage/basic_ps.html
VERY IMPORTANT:
If you re-position graphics or any video image in FCP, make SURE the VERTICAL setting for each KEY-FRAME (start, stop or hold) is always a EVEN INTEGER (Even Whole Number). Examples: 4, not 3 / -144, not -143.27 / 336, not 335.62 / 12 not 11.
The positioning settings/info (as well as many other settings) are found under the “Motion” tab in the Viewer.
Vertical position is the number in the RIGHT window in the area called “Center” (the horizontal position is displayed in the LEFT window).
I sometimes forget to check this and I can end up with images that look fuzzy when in-position.
This info applies to re-positioning anything on the Timeline: moving video, freeze-frames, internally-generated titles, and imported graphics.
It can be quite detrimental to the quality of your final output to not double-check this every time you reposition and/or re-size an image.