Do not operate the default value in the custom field

[mar22]

Hello

I added an custom field as a string (weight and price). He does not want to select the default value (minimum weight) eg. 50 g.
When I enter the details of the article a radio button is not checked. How to lead while clicking on the button "Order / buy" in the list of articles (not in the details of the article), the product jumped to a basket of minimum weight (that is, the default) and when I enter the details of the article a radio button mimimum weight it was checked?

if anyone has met with such a problem?
can anyone help solve this problem?

Best regards
Marcin