These settings can be changed via Settings > System Defaults.

Select the "Drawings" tab at the top left.

Any changes will only apply to new drawings that you create.

To learn about how these options work on the drawing tool canvas, read this article

Ruler Options: Show/hide ruler on the drawing canvas by default

Grid Options: Turn snapping on/off by default

Grid Snap: Set the visible grid-line size relative to the ruler unit of measurement

Unit of measurement: Set a default measurement type for this drawing (eg: metres, kilometres, centimetres, millimetres, pixels or none)

Ruler pixels per unit: Specify how the ruler should be spaced based on the selected unit of measurement.

Auto-scaling Asset Size: For assets which have their scaling set to "Auto", they will automatically be placed onto the canvas at this specified size.

For example, if the size is set to 50%, they will be placed at 50% of their original size.