Emails in inbox not displaying

A

AC Question

I have a Samsung Galaxy 4 and have my MSN email set up on the email app that came on the phone. Ever since I've had the phone, I have never been able to get all of the emails in my inbox to display on my phone. When a new email comes in, it will display until I delete it, either on my PC or on the phone. However, if I simply read an email on my PC and leave it in my inbox, it will no longer display on my phone. Wince the reason I leave emails in my inbox is so that I can retrieve the information in them later, this is a huge pain! Any suggestions?