Hi, I’m not brilliant at this stuff but I’m not bad at music theory …
Your grace notes are Appoggiatura. An appoggiatura commences on the beat of the note that it is attached to and takes it’s duration out of the note value that it is attached to. Therefore the retake is in the correct place.
An Acciaccatura on the other hand is played BEFORE the beat of the note that it is attached to stealing it’s time duration from the previous note.
Try changing your Appoggiatura to an Acciaccatura and see if you get the behaviour you’re looking for without fiddling with Dorico’s standard settings.