Multiple seleccion list without default is selecting ALL values

Multiple seleccion list without default is selecting ALL values

Hi

I created a multiple selection field on my Leads module, and I did not choose a Default value because we dont always need it.

But when we create new Leads, ALL of the values get selected automatically, even if we don´t "fill" that field, we still get ALL of the options automaticaly for all of our leads.

How can we avoid this???? it should be off automatically