How do I synchronize Outlook (Office for Mac 2011) e-mails with Outlook.com and iPhone e-mails?

I'm having difficulty connecting Outlook (Office for Mac 2011) with my Outlook.com and iPhone e-mails. Each can receive and display new mail, but if I delete or read an e-mail on one platform, it doesn't update the others. (And at least Outlook.com and my iPhone used to be synced...before I started messing with settings to get all three to connect.) Essentially I now have to open or delete each message three times and am on the verge of giving up on Outlook altogether.