1.1. Login as Sys Admin and open the System profiles,
Sys Admin: Profile > System
1.2. As we will change the color scheme only for our XX_USER so enter the user name in the User field and Java Color Scheme in the Profile field.
1.3. Click on Find (button).
1.4. Under the User name open LOV and select a color like I have selected blue.
1.5. Click the OK (button).
1.6. Save the data and logout from the Oracle Applications.
1.7. Now login as XX_USER and view the color change.
Note: The above change will only work for XX_USER as we changed color scheme only for this user. For a Site level change do not provide user.