To add or remove knots/lines, go to Image> Adding Removing Knots/Lines:
If you want to alter the canvas size of the design specifically by adding pixels around the selected area, then you can use this command. You can select the option of Add or Remove the number of Knots or Lines in the particular area symmetrically by selecting the option.
In this example, we will make the width of the canvas size bigger by 40 knots.
By default, you will see a gray line on the middle of your design on the resize window.
Click on those area where you want Galaincha software to add/remove pixels when you want to change canvas size.