MyBB Community Forums

Where is this part, I want to shorten the options to fit in one line.

Try to look for in footer template, its most likely bottommenu or tfoot, but wondering why thead is there in bottommenu.

It must be in forumdisplay_threadlist or something under Forum Display - Templates

edit values for below language variables in forumdisplay.lang.php
search_forum AND inline_thread_moderation

forumdisplay_searchforum template --> {$lang->search_forum}
forumdisplay_inlinemoderation template --> {$lang->inline_thread_moderation}

This is a colspan issue.

^ that forum has width as 65% !! should be 80% to adjust for the issue ...