The easiest thing to do is ask the users to clear their cookies. Otherwise, you will need to make this template mod everytime you do an upgrade. You need to edit every block_* template and look for something that looks like this:
HTML Code:
<a class="collapse" id="collapse_block_blogentries_{vb:raw blockinfo.blockid}" href="{vb:raw relpath}#top"><img alt="" src="{vb:stylevar imgdir_button}/collapse_40b.png" id="collapseimg_blogentries_{vb:raw blockinfo.blockid}"/></a>
I *think* you can just remove the collapse part and you will be fine. So, something like this:
HTML Code:
<a class="collapse" id="blogentries_{vb:raw blockinfo.blockid}" href="{vb:raw relpath}#top"><img alt="" src="{vb:stylevar imgdir_button}/collapse_40b.png" id="blogentries_{vb:raw blockinfo.blockid}"/></a>
I haven't tried any of this, so you may need to play with it to get it correct.