In order to completely override the bootstrap button styles, you need to override a list of properties. See the below example.
.btn-primary, .btn-primary:hover, .btn-primary:focus, .btn-primary.focus,
.btn-primary:active, .btn-primary.active, .btn-primary:visited,
.btn-primary:active:hover, .btn-primary.active:hover{
background-color: #F19425;
color:#fff;
border: none;
outline: none;
}
If you don't use all the listed styles then you will see the default styles at performing actions on button. For example once you click the button and remove mouse pointer from button, you will see the default color visible. Or keep the button pressed you will see default colors. So, I have listed all the pseudo-styles that are to be overridden.