Hello Jaime
I tried altering Stylesheets and Page template settings, but this did not had any effect on the responsiveness.
I don’t understand what is meant in the document of the second link you send.
I have no idea what or where I need to edit these code.
I will contact the theme developer, and I hope he can help me with this.
Otherwise, I need to cancel my order and ask for refund.
Best regards,
Bart