you need to scan the unsigned transaction with the camera, and it will open a transaction window with a sign button.
Thanks for answering. Should I scan the unsigned transaction from what tab? "Send"? Because when I scan from the "Send" tab it only show details about the transaction, recognizes as Unsigned, but won't show any button except for the QR-Code symbol and the Close button. No "Sign" button in this screen.
UPDATE: as I was posting in 2 topics, let's give preference to https://bitcointalksearch.org/topic/electrum-for-android-75617 as there's more detailed info. Thank you for answering, ThomasV. Could we consider producing a Manual to this matter?