If you keep your invoices, or scanned receipts in any 3rd party cloud storage service, i.e. Drop box, Gdrive, box, creative cloud etc.. you can access, and attach these files within your income and expense screen.
Hit Plus or Minus to access the recording screen
Tap the Receipt icon in the top right-hand corner
You'll see a list of your connected 3rd party cloud apps. Here, you can navigate to the designated folder from within your chosen storage service.
Note: If you don't see the application you're looking for, either of the following should solve this.
Click More in the menu and make sure it's turned on.
Or, open up the missing application and make sure you're logged in. You need to be logged in in order to access your account from the attachment menu.
If you have nay other questions, qualms or queries, hit the speech bubble in the bottom right-hand corner of your screen and give us a hola.