If you're running Windows OS, please refer to the following steps:
1) Navigate to COMMENT tab, select Typewriter tool, and click on the page. The current tab will be switched to COMMENT FORMAT tab.
2) Type anything on the page, highlight the text, and select Font Color with “A” shape under the COMMENT FORMAT to pick up a desired color.
If you are editing a block of existing text, double click on it to make the cursor appear inside the text box, and then highlight the text.
If you want to set the color as new default, please click on the typewriter text then right-click to choose "Set Current Properties as Default".
If you're running Mac OS, please select Typewriter text, and click on "Aa" icon on the toolbar, then select the color under "Format" to change color.
Note: If you want to set the color as new default, please click on the typewriter text then right-click to open "Properties" then check "Set Current Properties as Default" in the Properties dialog.