Hi,

Please try add more this code to Customize > Custom CSS to do that:

\
.vc_btn3.vc_btn3-color-juicy-pink.vc_btn3-style-flat:focus, \
.vc_btn3.vc_btn3-color-juicy-pink.vc_btn3-style-flat:hover, \
.vc_btn3.vc_btn3-color-juicy-pink:focus, \
.vc_btn3.vc_btn3-color-juicy-pink:hover,\
.vc_btn3.vc_btn3-color-juicy-pink.active, \
.vc_btn3.vc_btn3-color-juicy-pink.vc_btn3-style-flat.active, \
.vc_btn3.vc_btn3-color-juicy-pink.vc_btn3-style-flat:active, \
.vc_btn3.vc_btn3-color-juicy-pink:active,\
.vc_btn3.vc_btn3-color-juicy-pink, \
.vc_btn3.vc_btn3-color-juicy-pink.vc_btn3-style-flat{\
    color: #ffffff;\
    background-color: #ffff00;\
}\

Change color ffffff and ffff00 on the above code to any color code you want. You can get a color code here

Best Regards,

PenciDesign