By default, the platform does not have this option. You can use the following CSS code.
Please follow the steps below:
1. Go to BuddyBoss > Theme Options
2. Under Custom Codes, enable CSS
3. Append the following:
#whats-new-form #bp-activity-privacy-point { background: (color code)!important; }
4. Save changes.
Screenshots
Without code
With code