Can't access all messages

I used IMAP to access a gmail account from Outlook within Office 365.  I turned on the option to see the total counts in a folder to make sure the totals matched what I could see logged into Gmail and they do. I have one parent folder and 5 children folders under the parent, each with varying numbers of email in them.  All of the total counts match what is in gmail, however I cannot see all of the email in the folders.  For instance, the parent has 2592 messages and I can only see back to item 118 (Dec 17, 2018).  In Gmail I can see the items all the way back to the 11/2009 original email.  How can I access the entire set of messages in these folders?