When you’re ready to send bitcoin using the Casa App, start by tapping your "Assets" tab in the middle of the bottom navigation bar:
There, you'll see your multsig balances and Mobile Key balance. Click into any of the balances to send or receive funds as well as view transaction history.
When sending, note that you can optionally use previous addresses by selecting “SEND FROM” drop down above the amount. This allow you to choose which addresses to spend from.
When you choose a recipient, note the shortcut to your other wallets available under “address” or “scan code”. Once you have your multisig set up, it will appear in your shortcuts as an option.
When sending & receiving, you’ve got the option of scanning a QR code, copying and pasting an address, or entering an address directly.
Then, click "send."
If you're sending from your mobile key, that's it. You don't need to take any further action.
If you're sending from your mobile key setup, then you must add signatures from your mobile device as well as your hardware device. Once those signatures are added, click "Send" to confirm.