How to change background color of next/prev/submit/retake buttons

I’d like to change background color of the buttons next/prev/submit/retake.

I’ve already used code from other topic, but it changed button’s position to the left bottom. I’d like to left current positions (the same as on the current website): next and submit on the right, prev on the left.

What should I change in Custom Style CSS??

Here is the code I used:

.qsm-submit-btn, .qsm-next, .qsm-previous, .qsm_retake_button{
background: #946926 !important;
color: #ffffff !important;
border-radius: 10px;
}

.qsm-next{
position: relative;
top: 15px;
}

.qsm-previous{
position: relative;
top: 15px;
}

.qsm-submit-btn{
position: relative;
top: 15px;
}

The page I need help with: [log in to see the link]