Change octave lines behaviour

Hey there!
How can I change the octave line behaviour shown in image 1 to set the 8va only to the dotted quarter, as in image 2?

Thanks!
Albert.
Captura de pantalla 2017-05-05 a les 9.59.22.jpg
Captura de pantalla 2017-05-05 a les 9.59.09.png

It should be as simple as selecting the dotted quarter, typing Shift+C for the clefs and octave lines popover, typing e.g. “8va”, and then hitting Alt+Return to create the octave line to apply only to the current voice, rather than to all voices on the staff.

Oh, thank you very much!

Thanks Daniel for your advice!
Alt clicking the octava bassa button after selecting some notes from a voice did beautifully the trick!