In the word toolbar, click Review, as shown in the following figure:
Under Review, find Revision and click the down arrow under Revision to open the drop-down menu, as shown in the following figure:
In the drop-down menu above, click and select "Revision Option" to open the revision option setting box, as shown in the following figure:
In the pop-up revision option setting box, you can set the colors of the revised inserted content, deleted content and comments respectively, as shown in the following figure:
After setting the color, click OK to set the modified color, as shown below: