I'm trying to create the music sheet of "Recuerdos de La Alhambra" with Sibelius music notation software.
How to create tremolos in Sibelius?
I Use Sibelius G7.
Tremolos are located on third pane of Keypad.
Press CTRL+ALT+K (or menu Windows->Keypad) to display Keypad window, and then "+" key on numeric keyboard (or just use Your mouse to click) to navigate to third pane.
You have options from 2 up to 32 tremolos.
Examples of tremolos in Sibelius G7