I am a Premier Platinum member with United and sometimes when I change my flight online at united.com I am not assessed a change fee and other times I am. Why is that?

United, like other major carriers, has a $200 change fee for domestic tickets and a variable change fee for international tickets, and does not waive or reduce these fees based on frequent flyer status. However, for Gold, Platinum, and 1K level travelers United does waive the “”same day flight change …