I'm going to take another stab at the problem I tried to explain below. When I click on the "message" icon, the default view that opens includes both my inbox and sent items. The sent items have check marks by them and the inbox items are at the top of the list, but it's really cluttered this way. Is it possible to make it open only the inbox rather than the combination of inbox and sent items? Thanks.

No! It's not an Inbox. It's called the Messages folder. You can set a filter to show only in Incoming messages, but it is not persistent.

see : Any way to only view incoming messages?
For info on how to set up a permanent filter/search rule to help clear out your 'sent items' from the "message list"