Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
The date you pay your subscription on is linked to the date you started the subscription and they do not provide any available method to change the date your subscription payments are deducted from your account on each month.
The only working method to change the subscription payment is to cancel the subscription on your account online maybe a couple of days before your preferred payment date, disable the recurring billing on the subscription, then take out a new subscription on your preferred payment date.