It's straightforward.

Create a set of tools like found in Photoshop ( or any design software ) which allow objects ( text, images, shapes, stamps, etc.) to be selected and aligned to:
1. an object
2. the canvas

Additionally, add a tool for grouping and ungrouping objects and one to "send to the back" or "bring to the front" (practical when objects overlap ).

GoodNotes is a note-taking app, and it should be equally considered a design app. Missing these simple tools that allow me to organize my content makes GoodNotes less effective and less efficient ( and often frustrating ) at its intended purpose—organizing one's notes.

Link to Adobe Photoshop page describing functionality:
https://helpx.adobe.com/photoshop/using/aligning-layers.html