To select any object (handwriting, text, shapes, images, or highlights), choose the Lasso selection tool ( ) or Rectangular selection tool ( ) from the tool picker, then select one or more objects by drawing around the items you wish to select.

Tip: You can select a single object by tapping on it with either selection tool or select everything on an entire page using the Select all feature.

For a video tutorial, see Squid - Selection Tools. There's also an outdated (😉) Squid - Tools Overview video that shows a bit more about what you can do with selected objects.