Shortening rests at the beginning of a measure

I had written the two measures as they are in the image at the beginning,
and then I wanted to change them to what in the image is the fourth measure.
I had no problem changing the half and quarter notes on the left and right hand,
but I had not been able to change the quarter note rest at the beginning of the first and second measure.
i have ended rewriting the piano right hand.
Is there a way to shorten the quarter note rest at the beginning of the first and second measure
to eight note rest without messing up with the tuplets?
shortening written rests.PNG

You can shift selected notes to a rhythmical position to the left or right in steps following the current grid (shown in the lower left corner of the Dorico window). The key combinations are Alt-left/right arrow. If you set your rhythmic grid to eighth notes (quavers), you can easily move the arpeggiated motives to the second eighth note, without messing up the grace notes. I don’t think your grace notes are actually triplets, and they don’t need to be.

Thanks Peter,
I was using Shift-Alt-left/right arrow
instead of just Alt-left/right arrow,
So I was shortening or expanding the duration of the arpeggiated quarter note instead
of just moving it to another place in the measure without modifying its rhythmic value.