Here’s how to change your default Google account that also changes your default Gmail on Windows or Mac PCs. Google also assigns the first login as the default, which is why you need to sign out of all accounts first.
Google always opens new windows using your default account. This is because you access Google via a browser on either system. Whether you are a Windows or a Mac user, you will be happy to know that things work the same on both platforms. How to Change the Default Google Account on a Windows or Mac PC
