Onedrive and Dropbox Syncing Confusion

My problem is as follows:

A file in dropbox opened, edited, and saved on one computer back to dropbox is not showing changes when opened on another computer from dropbox. A file created and saved in dropbox is not showing when trying to locate from another computer. 

I have read many articles about the issue and am overwhelmed. My internet connection is secure, though I am operating from two different internet sources and two different computers. My app is up to date on both computers. 

I am not sure if this is related but I have read (and experienced) the "brown box icon" issue displayed over my document name - I thought this was dropbox syncing issues but have come to find it is a microsoft onedrive issue... I think. 

I do not understand why I am unable to see the updated/created file(s) saved to dropbox if created on two different computers, if that makes sense. My thinking is that if the saved location is dropbox (the source) then I should be able to view any updates/changes to a document once saved and closed from any computer source. 

Is this incorrect?  Is Microsoft OneDrive creating an issue? I never save anything to Onedrive, always to Dropbox when it comes to work related documents.