First please note, that when you activate the Spamshield it adds three new fields on registration form. The original forum registration form looks like this:

Regarding to editor buttons. For some reason your theme CSS affects all buttons and sets 160px width. To fix this conflict please put the CSS code below in Dashboard > Forums > Settings > Styles > Custom CSS Code textarea. Save it, delete all caches and do Ctrl+F5 on forum front:

#wpforo #wpforo-wrap button, 
#wpforo #wpforo-wrap input[type="submit"]{
min-width: auto; height: auto;
}
.wpforo .section-content-page{
max-width: 76%;
min-width: 800px;
}

Also, I'd recommend change the forum style to Red style in Dashboard > Forums > Settings > Styles admin page. Once you changed and saved, also change the #12 Primary color to your theme color #C62641