But I dont know how to do it. Thanks in advance.

I want to change the selected option from 233 to 75

But. I don't know how to change it...

You can set this preference to the ISO of the country you want to be used as the default in your Solidus initializer. If you are not sure how to do that, you can see the guides here https://guides.solidus.io/getting-started/installing-solidus#first-time-configuration

Keep in mind this will affect all forms where the country select shows.

Done. I've added

config.default_country_iso = "FR"

to the

config/initializers/spree.rb

file...

...and it works fine. 🎯 😀 Thanks a lot @Chris Todorov.