If you use more than one internet account, be aware of how to switch between each account within Apple’s suite of internet account apps. The name of your accounts will vary, but the below screenshots illustrate how a Google account will display alongside an iCloud account.
Internet Accounts, and the Mail app
In the screenshot above, the combined Inbox (A) is selected (If you can’t see the Inbox, choose Show Mailbox List from the View menu). As such, the middle column lists the inbox contents of both the Google and iCloud email accounts combined. Selecting the iCloud inbox (B) or the Google Inbox (C) instead would display the contents of the respective mailbox, only.
Internet Accounts, and the Contacts app
In the above screenshot, All Google is selected (if you can’t see the sidebar, choose Show Groups from the View menu). As such, the middle column will display all contacts stored with the Google account, only. To see any contacts stored in iCloud, we’d need to select All iCloud in the left column.
Internet Accounts, and the Calendar app
In the above screenshot, the iCloud account (A) and Google account (B) are indicated (If you can’t see your calendars in a sidebar on the left, choose Show Calendar List from the View menu). Note the colours of these calendars, and the calendar events. Can you identify which calendar the events belong to?
To move an event to a different calendar, click on the event, and a pop-up menu will be revealed.
On the top-right of the event’s popup, you’ll see another dropdown menu featuring a coloured square, indicating the calendar with which it belongs. Clicking this will reveal a list of your calendars.
Note that, once an event has been moved to a different calendar, the colour of the event will change.
Internet Accounts, and the Notes app
In the above screenshot, the Google account is selected, and, as such, the middle column lists any notes stored with it, only (If you can’t see the sidebar, choose Show Folders from the View menu). New notes can be accessed and stored with either iCloud or Google.