Global Duration Help Needed: 6/8 to 2/2 (Given an incorrect notated score)

I was given a score that was notated in 6/8 but it is entirely dotted quarters and dotted half. No subdivisions of three. I’m just needing to move it into 2/2 and turn all the dotted quarters into halves and all dotted half to wholes. This will give the real feel of the pulse that the music is in. When I change the meter, I get the bars shifted and the “durations” are the same. I have not found a way to fix this with the edit durations globally. Is there a quick way to do this? Using Dorico5 for Mac

Select All.
Engage Insert mode (I).
Hit . (removes all dots)
Then do Write>Edit duration>Double note durations.
Disengage Insert mode

There are things that can go wrong, particularly around rests, but this may be sufficient!

This is correct behaviour. A time signature only affects how notes are displayed, it does not change their duration.

(And welcome to the forum!)

Thanks ! That seems like it should work, but should I change the meter first or second?

It makes no difference. Try it both ways and see.