Jode,
Engraving Options > Dynamics > Relative to beats > Alignment of text dynamics relative to note:
Set as you like, then (bottom left of the dialog) Save as Default.
Oh, I did not remember that. Thank you so much, Pianoleo. 
For some reason, does not work for me. After clicking ‘Apply’ and ‘Save as Default’ (having any new unsaved or old already saved project open), I get an error message (see the image), and no defaults are saved (within a file, the settings sure are saved). I guess Dorico is trying to save a ‘settings file’ containing the defaults, but is unable to do it. Ideas?
There does seem to a problem here, too. On Mac I don’t get an error message, and it does save to the open project but it DOESN’T save as a default for future projects.
I tried the same process for switching the appearance of “subito” and “sub.” (at the top of the same dialog) and that seems to save as a default, correctly.
Interesting. So this new, warmly welcomed dynamics alignment option is some kind of a problem child. 
I’ve been unable to reproduce this problem, for what it’s worth. Can you try holding Alt in the Engraving Options dialog and clicking ‘Remove Saved Defaults’ to remove the saved defaults file, then try ‘Save as Default’ again?
The left hand version looks much better to me. In looking at the right hand alternative, it seems to me that it looks somehow cold and mechanical.
It occurs to me that what I have always done when writing an f or p dynamic by hand is to start by centering the top of the letter under the note, such that the rest of the letter comes naturally to the left. What I do with ff or fff, I cannot at the moment recall!