@ChristineDawley ...
The most common reason I've seen for what you describe is because people have Canvas saved as a bookmark/favorite in their web browser. So, if this is the case for you, maybe that bookmark/favorite is taking you directly to the "Chat" in one of your courses? If so, you would want to edit that bookmark/favorite URL so that it is pointing to your Canvas Dashboard instead of a specific area of a course. For example, you'd want to edit the URL so that it looks something like this:
https://SchoolName.instructure.com
...where SchoolName would be replaced with your own school name.
Hopefully this will be of help to you. Sing out if you have any other questions about this...thanks!