Changing creation dates of .PNG files mac

[SalvageCrew]

Hello
For the life of me, I can't figure out the syntax to change the create date of the .png 
the metadata listed from exif shows the only correct date listed in this tag.

Date Created                    : 2018:07:18 09:58:58

but I cannot get exiftool to read this and change the -FileModifyDate

I'm sure it's simple, but I can't figure it out..

Thanks for any assistance you can give me.

John

[StarGeek]

Try
exiftool '-FileModifyDate<DateCreated' /path/to/file.png