Hi Drew,
I can confirm currently there is not a feature to allow you to set what page opens when you open up an Application via the app bar. There are default dashboards that can be set up for when a user first opens an application but not to set behavior for what happens when they use the app bar to change applications. If being able to set a default behavior for when the app bar is used to navigate between applications would be beneficial Drew I would suggest submitting that via our User Voice as feedback. I see that from your other post you are familiar with User Voice but for others who might find this and wonder where to put their feedback I have included a bit more about User Voice below.
User Voice is a tool used by our Product Management team to gauge user interest in future features and enhancements to existing features. The Quick Base User voice can most easily be accessed from the My Apps page in Quick Base by clicking on the orange Feedback tab that appears on the right of the page or at
http://quickbase.uservoice.com by signing in with your Quick Base credentials. It allows other users with similar needs to add their vote and show their support for ideas. I often recommend when an idea is submitted to user voice that a link should also be posted here in this thread so that others with the same need can add their vote. Thank you very much for your feedback Drew.