To change the account that's tied to your Nearby Sharing settings, you'll need to do the following:
1. Click on the Start menu, then select Settings (gear icon) > System > Shared Experiences.
2. Under the Nearby Sharing section, click on "Change default account settings."
3. You should see a prompt that says "You need to sign in with a Microsoft account to use Nearby sharing." Click on the "Sign in" button and sign in using the Microsoft account that you want to use for Nearby Sharing.
4. Once you've successfully signed in, you should see the account listed under "Accounts used by other apps" in the Shared Experiences settings.
Once you've completed these steps, you should be able to use your preferred Microsoft account with Nearby Sharing. If you still have issues, make sure that your devices are connected to the same network, and that both your Windows device and Android phone are Bluetooth and Wi-Fi enabled. Additionally, make sure that your Android device is running Android 6 (Marshmallow) or later and that Nearby sharing is enabled on your phone.