If you open up SHOWTHREAD template, do control-F for this:
Code:
<vb:if condition="$show['largereplybutton']">
Should definitely be there. Delete that and the corresponding closing tag </vb:if>
There will be one on top and one on the bottom.
Under ForumDisplay, do the same for:
Code:
<vb:if condition="$show['newthreadlink']">
Two instances (ignore the middle third one)