Drop-down list last value should be remember

[etxnreg]

Hi,
I have a problem with drop-down list that I can not solve.
I have some drop-down lists and I would like to remember the last value when I use the back button or return to the site again.

Grateful for any assistance

Niklas

<form name="next" method="POST" action="igp.php" style="margin:0px">

<select name="slot1" style="position:absolute;left:979px;top:361px;width:48px;z-index:13">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<select name="port2" style="position:absolute;left:1087px;top:402px;width:47px;z-index:23">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
<input name="Next" type="submit" value="Next" style="position:absolute;left:1375px;top:719px;z-index:132">