Many operations (changing color, shape, font etc) can be applied to multiple topics simultaneously. For this to work, you much first select those topics. This page describes how.
Selecting topics on Mac/Windows is pretty standard.
- Click on the background canvas and drag to create a selection rectangle. This requires 'Drag to move canvas' to be unticked in the Preferences/Settings. If this setting is enabled, then you can click + hold + drag to create a selection rectangle. Shift + click + drag will always create a selection rectangle.
- CMD (on Mac) or CTRL (on Windows) + click will toggle the selection state of a single topic.
- SHIFT + click will select sibling topics between current selection and clicked topic.
- SHIFT + arrow key will select adjacent topics.
- Right click on a topic and choose the Select menu for more options (select all children, siblings, cousins etc.)
iOS - please see here