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:
/* Normal state. */
.site-header .button.signup {
background: red;
border: red;
color: white;
}
/* Hover state. */
.site-header .button.signup:hover {
background: red;
border: red;
color: gray;
}
4. Save changes.
Screenshots

