Hello @Currtsyy thanks for getting in touch with us.
You should be able to change your region and opponents by selecting your profile name on the top left of the menu, selecting 'change region', and then select a region of your choice. then 'confirm'. If you then select a game mode such as campaign mode, you will then see your newly selected region displayed as well as track times and players from that region. After completing the track, you will see how you compare against players in that region. Sometimes it can take a few minutes for these details to update however, so you may see menu screens displaying your previous regions times etc from time to time.
If this is not the case for you, are you able to show us a video that shows this option not working correctly?