I've found no application-level preference for this in FMP.
One recommendation that I like is to use the grid when creating one's own Guides, but then turn the grid off and rely on your saved Guides for general spacing and dynamic matching grids for auto-aligning, rather than having the main grids On. You can share your Guides across layouts without the smaller grid spacings.
If your solution is hosted, then changing the units won't stick. You need to open the solution locally (not hosted), set the units to points, set other stuff, and then put back on the FM server.
Other items that can't be changed in a hosted solution are, the initial position and size of the first window that gets opened. The setting to view sample data when in layout mode, and so forth.
Doh! You know after 15 years using FileMaker you think I would have thought of that.
Doug from BowdenData wrote, in part:
If your solution is hosted, then changing the units won't stick.
I once inherited a hosted system of over 60 files where virtually all of the default settings for everything were inconsistent across the files. I spent way too much time getting my Inspectors reset to the right defaults to work with each time I entered layout mode during the entire time I worked on that live system!
If you've got a single file or a small number of files, take them down, reset everything locally, and then rehost. It will save time in the long run.