Changing "Create Date" to Sync with Google Photos

[Kmartee]

Hello Exiftool Forum,

I am new to the forum, and I have been seeking solutions throughout the web and haven't found answers, hoping to inquire within for an easy solution (I hope).

I am running on Mac OS version 10.14.5 (Mojave) planning on updating to 10.15.1, working with Exiftool I downloaded 11/2018.

My issue is this:
I wish to change the "Create Date" of digital photos I have from family, and also those that I have scanned onto my computer, so that they can be Dated correctly when they appear on my Google Photos.

I have used different terminal commands to change the "Date Modified" and "Date Created" (i.e. touch -t & SetFile -d 'MM/DD/YYYY') however, this has not changed the "Create Date" of the image file. I have used "Exiftool -a" in terminal to view this and it also shows up when I upload the image files to Google Photos.

I have also had a couple of instances of "Warning: [Minor] Duplicate XMP...." occur when trying some of the other exiftool commands to change the date.

Any help would be appreciated, I am not very Code/Computer Science savvy and any help would be appreciated