Same with me here. It is useful for quick scrolling to top and bottom especially for forum with plenty of categories and boards like yours.
If you want it (go up / go down) to be in fixed obvious positions in all pages, while viewing in mobile, other than restoring the default, may be you can just customize your index.template.php, like this for example:
Find:
<form id="search_form" action="', $scripturl, '?action=search;sa=results" method="post" accept-charset="UTF-8">
Add after that:
<a href="#bot" id="gobottom2" title="'. $txt['go_down']. '">↓</a>
And find:
theme_copyright(), '
</li>',
Change that to:
theme_copyright(), '
</li><a href="#top" id="gotop2" title="'. $txt['go_up']. '" style="float: right; padding-left: 10px;">↑</a>',
Hide it in normal view and show only in mobile view by adding this to custom.css:
#gobottom2, #gotop2 {
display:none;
}
@media screen and (max-width: 33.750em) {
#gobottom2, #gotop2 {
display: block;
float: right;
padding-left: 10px;
}
}
Or something like that...