When working with a shape or connector in a model you can change the way it looks by
Selecting the required options from the Edit toolbar
Selecting the required options from the Format menu
Applying a style
Using styles, you can apply a group of formats in one simple click.
NVivo provides a default style and, if required, you can change its formats. You can also add new styles.
You can create and edit model styles in Application Options and Project Properties.