MS Office 365 and Outlook help needed, simple but exact task needed?

I have 1 email account 1 domain but a PC a Laptop and a mobile device (Iphone) I need to sync all 3 of these devices with this email account using outlook on office 365, can anyone shed some light in the matter, also what is MS exchange, I quite didn't get what is it for.
My main problem is that I do not see the sent items from each device, only the received ones. And the sent items are only accessible from the device used to send them.

I have 1 email account 1 domain but a PC a Laptop and a mobile device (Iphone) I need to sync all 3 of these devices with this email account using outlook on office 365, can anyone shed some light in the matter, also what is MS exchange, I quite didn't get what is it for.
My main problem is that I do not see the sent items from each device, only the received ones. And the sent items are only accessible from the device used to send them. Thank you already Just sign in to the same account on all 3 devices. They will (at least my phone, tablet, pc do) sync automatically. On each device you can select which folders appear on which device (Inbox is automatic. The others need to be selected).

Exchange Server is the software in Office 365 providing you with an email service. Have you followed these steps:

http://www.360sync.one/office-365-windows-outlook-sync/

If you have, you may need to visit here

https://community.office365.com/en-us/f thank you both so much, not sure can I award best answer to both posts, either case thanks again, this helped will try it out, certainly I hadnt done this to the extent I needed to. Very useful.

Have you followed these steps:

http://www.360sync.one/office-365-windows-outlook-sync/

If you have, you may need to visit here

https://community.office365.com/en-us/f

Thank you both so much, not sure can I award best answer to both posts, either case thanks again, this helped will try it out, certainly I hadnt done this to the extent I needed to. Very useful.