I read your question, I even looked at your page. As I said, I didn't understand your question. And as the only person here who has tried to help you I would hope you would have a little patience in trying to explain what you want.
I stand by what I stated before, your 3 fields and labels are already vertically aligned inside the table row/cell you have on your page.
What I think you are really trying to do is to make them all stay on a single horizontal line? Right?
Then try adding the nowrap attribute to those table cells.
<table width="530" border="0" cellspacing="0" cellpadding="0">
<tr>
<td nowrap>{category_dropdown_form}</td>
<td nowrap>{imgsort_dropdown_form}</td>
<td nowrap>{setperpage_dropdown_form}</td>
</tr>
</table>
This is just basic HTML editing.