I use European format YYYY-MM-DD in my form, but Acrobat wants DD/MM/YY
dd/mm/yyyy is also quite europan unlike the mm/dd/yyyy the americans use.
How are you adding the date field to your agreement? dragging and dropping, text tag, or acrobat form field?
I use Acrobat form field where my yyyy-mm-dd format is an option. When I try to send the form I have to "correct" the date format to the american format
I assume you using a regular Acrobat field and using the Format tab in the field properties? If so Adobe Sign does not support that.
You need to use a special syntax for the naming of you field, called text tags.
what kind of date field is needed? Do you need an automatic date field that populates the current time, or do you want the signer to enter a date?
See following link about text tagging and acrobat forms for Adobe Sign use