Here’s how you can adjust Outlook for Mac to pull up your iCloud contacts first when composing emails:
Set iCloud Contacts as the Default Address Book:
Open Outlook on your Mac.
Go to Outlook in the top menu and select Preferences.
In the Preferences window, click on General.
Look for an option like Default account for new items (or a similar setting, depending on your Outlook version).
Set iCloud as the default account for new items. This may help Outlook prioritize your iCloud contacts.
Check the Address Book Order:
Still in Outlook, navigate to the Tools menu and click on Accounts.
In the Accounts window, verify that your iCloud account is listed and active.
Then go to the Address Book (or People) section of Outlook and check if there's an option to reorder the contact sources, placing iCloud at the top.
Adjust Search Preferences:
When composing a new email, in the "To" field, start typing the name of a contact.
If Gmail contacts are being suggested first, click on the dropdown menu beside the search results. You should see an option like "Search [Account]"—select iCloud Contacts instead. Outlook may learn from this preference over time.
If these steps don’t solve the issue entirely, it could also be worth checking your Mac’s system preferences to ensure iCloud is fully synced and prioritized:
Open System Preferences > Internet Accounts, then select your iCloud account and confirm Contacts is checked.