On your Android device, locate and open the Google Play Store app. Once the Play Store opens, tap on the menu icon (usually represented by three horizontal lines) in the top-left corner of the screen. In the menu, scroll down and select "Sign In."

First of all, they're different accounts. Your original Gmail address is your Google account, and it gives you access to Google's services and devices. Even if it's associated with a Gmail address, your Microsoft account is a different account that gives you access only to Microsoft's devices and services.