There may be some tools that you might not be able to find in Paint Shop Pro X that you may wish to add. Here's a quick way to do that.

This tutorial will show how to add the Automatic Contrast Enhancement Tool to a menu but the same procedure is used whether you wish to add one to another menu or a tool bar. It's really just drag and drop.

Right Click on a blank area of your work space and choose "Customize" from the menu.

A window containing tabs of choices will appear. I've broken the image in parts rather than show the whole size but you only need to go to the first tab, "Commands".

Grab the tool you wish with your mouse and you'll see a little box attached to your mouse. As long as you hold your mouse button down it will stay stuck to your mouse. Don't release it until you have it where you want it to go.

Keep your mouse button down and drag all the way to the menu on the top that says "Adjust". You'll see the sub menu appear as you get to the Main Adjust title.

Keep dragging down the sub-menu until you reach the heading that this tool should go. In this case it is "Brightness and Contrast". when you reach that area another sub menu will open. Keep dragging until you get into that menu and you can drop it. The example below shows that I'm dropping the box just below "Brightness/Contrast".

When you are finished just close the Customize Panel.

The next time you open the Adjust menu and go to Brightness and Contrast, you'll see the Automatic Contrast Adjustment there.

Use the same technique to add tools to tool bars or anywhere else. The example on the right shows I'm adding a "New Raster Layer" button to my Layer Palette.