Spacing between individuals notes can be altered using the note properties dialog boxes. But for fine-tuning the amount of horizontal space occupied by the music, here is another way:

Wherever you wish to stretch the notation, go to the top staff and insert a few spaces of text, using "preserve width." Once this is set up, you can repeatedly paste the spaces by clicking at the location to be spaced, type "x" to bring up the text editor, then "enter."

When you setup your page to "extend last system," sometimes the notes bunch up at the left. With extra spacing, they can be expanded to fill the system more attractively.

Spacing between the notes of individuals can be changed by using the zones of dialogue of properties of note.  But end-to grant the quantity of horizontal space occupied by the music, here another manner:

Everywhere where you wish to stretch the notation, to go to the more senior employees and to insert some spaces of text, by using "the preserve width" once that this is installed, you can on several occasions stick spaces while clicking to the place to space, type "X" to bring to the top the text editor, then "enter"

When you install your page "to prolong the last system," sometimes the notes gather to the top with the left.  With additional spacing, they can be increased to fill system more agreeably.

(Translation E->F->E by BabelFish@Altavista, worst being E->F...)