Centering the submit button

I have managed to centre the Submit button on one of my order forms using coding but I cannot do it on my other form which is the same layout.

Please add this custom CSS code:

.form-all .qq-upload-button, .form-all .form-submit-button, .form-all .form-submit-reset, .form-all .form-submit-print {

    margin-right: 15% !important;

}

You can adjust the margin percentage to your own preferences.