Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi MrDaffyD43,
To let updates made in one Office 365 account show in all Outlook clients of five computer, you can set up your Office 365 account in all the Outlook clients via Exchange mode. Exchange mode means use Outlook automatic account setup described in the article below to set up your account in the Outlook client.
https://support.office.com/en-us/article/Outlook-email-setup-6e27792a-9267-4aa4-8bb6-c84ef146101b
Under this configuration, updates made in any Outlook client of the five will be shown in other clients.
Regards,
Larry