As a long-time Chrome user and tech expert, I know how frustrating it can be to manage multiple accounts on a shared PC. Chrome's multi-profile feature is a game-changer for separating work, personal, and family use, but first, you need to know how to change the default Google account. Here's my proven method to make it seamless.
Chrome's support for multiple profiles gives you granular control over settings, extensions, and customizations. To switch profiles or set a new default Google account, follow these straightforward steps:
On mobile devices, the default account may depend on your OS and apps, but the process is similar.
Chrome remains the top choice for Windows users due to its speed, reliability, and vast extension library. By default, it loads your signed-in account—but you can change that easily.
To start, click the Profile icon in the upper-right corner and select Sign out. If unavailable, go to Manage your Google Account.

Then, on the Google page, click the Profile icon and select Sign out from all accounts, as shown above.
Head to gmail.com or another Google service and sign in with your desired account details.

Note: The account you sign into becomes your new default. Verify by opening Google Drive or another service via a new tab and the Google Apps icon—it should use the updated account. Switch accounts anytime as needed.
Though related, they're distinct. A Chrome profile handles browser-specific settings like extensions and themes. Your Google Account governs access to services like Gmail, Drive, and Photos.
Open Chrome or a new tab, click the Google Apps icon (grid) next to your profile. Choose from defaults like Gmail, Meet, Drive, Calendar, or Photos.
With years of guiding users through browser tweaks, this method has helped countless people streamline their workflow. Hope it works perfectly for you!