Your browser has regional setting which are taken from your computer's regional settings during installation. Even though your IP address changes, your browser will still send its configured regional settings to websites as you navigate. Those websites may also have added region-specific local settings and database entries to your browser that will reveal your actual location despite your changing IP address. You may need to make your browser's language a bit more ambiguous, and clear any latent local settings and database entries to fully mask your original location.