It may be you canceled too late and still owe the money. You should pay the balance and then try to get a refund. Until you resolve this, Apple won't let you change country settings.
From --> If you want to cancel a subscription from Apple - Apple Support - "If you signed up for a free or discounted trial subscription and you don't want to renew it, cancel it at least 24 hours before the trial ends." At this stage the renewal is considered a purchase. For a new subscription the sale is probably effective from when you first agree to subscribe.
If you use Family Sharing and you are the organizer, make sure this is not something purchased by another family member. Subscriptions and purchases made by family members under Family Sharing (if applicable) will not show in your list or purchase history. The email receipt you receive from Apple will show the Apple ID of the purchaser but not what was purchased.
If neither you nor a family member (if applicable) has a record of this purchase and you only saw it on a statement for a card you alone control, contact your bank or card company about card fraud. Apple does not handle that.
If you do recognize it and have canceled the subscription and wish a refund: Apple's terms of purchase in the USA are, "All Transactions are final" (Legal - Apple Media Services - Apple ), but some countries have different laws so check terms for your country at: Legal - Apple Media Services - Apple If sales are final then it is Apple's decision if they want to grant a refund. You can always ask, and people do get refunds on a case by case basis, but Apple can also say no. To request a refund:
Request a refund for apps or content that you bought from Apple - Request a refund for apps or content that you bought from Apple - Apple Support
Report a Problem - https://reportaproblem.apple.com/?s=6
If a reporting a problem request is unsuccessful you can also try clicking here --> Choose your country or region - Official Apple Support Select your country, then a product.