Hi ionaeratcliffe-g Thanks for reaching out to us here on the Community. It's not possible to download a list of invoices and expenses from the app. It is however possible to run a number of reports or a list of invoices/expenses and export them when you've logged into your account via a browser on your mobile device.
We will submit your valued feedback to our developers and hopefully they maybe able to implement in the future a more robust reporting function on the app.