To change a line color, you have two optional ways:
Use the Format menu.
In version 11, the Format menu will be opened automatically at the right side when selecting an annotation.
In version prior to v11,
1. Select Hand tool, click on a target line on the page.
2. Select Comment Format menu bar
3. Click on the exiting color palette or the Line Color to select a color.
Use Line Properties tab.
1. Select Hand tool, right click on a target line on the page.
2. Select Properties to open the Line Properties.
3. Click on the color icon to pick up a color you want.
To apply the current color to all lines drawn afterwards, right click on the line, choose Set Current Properties as Default.