The value attribute for an input type submit is the Text that you see in the button. title is what you see if you hover over the button.
For this Quick Reply box:
Attachment 96332
HTML Code:
<input type="submit" class="button" value="Post Quick Reply" accesskey="s" title="(Alt + S)" name="sbutton" tabindex="2" id="qr_submit" onclick="clickedelm = this.value" />
<input type="submit" class="button" value="Go Advanced" accesskey="x" title="(Alt + X)" name="preview" tabindex="3" id="qr_preview" onclick="clickedelm = this.value" />