When you link your accounts, that will allow all events such as:
Follows, Donations, Subs, Etc.. to all show on the same widget URL for all accounts.
To do this, you would first want to start by linking your accounts in your account setting.
Once you've linked your account, you now have the option to set an account as the primary account. The primary account would be the one that is shown on your donation page and would be the one your donation URL is bound to. Each account you have would all have different donation URL's, changing your primary account would typically change your donation URL to the URL generated for that account.
Once you've chosen which account you want to be your primary account, you should not change the primary account again, unless absolutely needed as changing your primary account can cause issues with your donations and/or other settings like alerts, themes, etc..
Now, for the fun stuff! This is easier than it may seem, but can be confusing at first.
In the next screen shot you will see that on our site, you can change the platform that of which you'd be editing your alert/widget settings for. If you'd like to edit settings for another linked account, you would need to switch the platform that you're editing your settings for.
As you can see in the screen shot above, we have Twitch as the selected platform. For that reason, when we are in our alert settings (or any widgets settings for that matter) we will only see settings for our Twitch events. If you wanted to edit the alerts/settings for other linked accounts, you'd want to switch platforms via the platform logo/button at the top right of our site, seen in the screen shot above.
As you can see in this next screen shot, we've changed the selected platform to YouTube. Since we've changed our selected platform to YouTube, we can now edit alerts and other settings that would be specific to the YouTube account you have linked to your account.
That's all there is to it, you can now have custom alert and widget settings for each account you've linked in your account settings.
Now when you receive alerts and other events from each of your linked accounts all working from the same widget URL's.
No need to change widget URL's if you plan to stream with a different account than what you have set as your primary account.