Follow these steps to adjust the ink color and thickness in OneNote for Windows 10:

1. Open the Onenote application

2. Select the Draw tab which will appear at the top

3. Look to the right panel and locate the Pen tab

4. Click the drop-down at the top of the Pen tab to select the color of your pen

5. Find the slider bar to adjust the ink thickness

6. Click apply at the bottom of the panel to save your changes