[Lucky Seven]

I'd start with Modify User Options Templates >> modifyavatar

The code for the submit button should look like:

<input type="submit" class="button" value="$vbphrase[save_changes]" accesskey="s" />

If the information is simply being cleared out when you intend to save, some of the content in the code may look more like this, which is the reset button:

<input type="reset" class="button" value="$vbphrase[reset_fields]" accesskey="r" />

The default vB design includes both options, as shown below:

<input type="submit" class="button" value="$vbphrase[save_changes]" accesskey="s" />
<input type="reset" class="button" value="$vbphrase[reset_fields]" accesskey="r" />

That would be my initial guess for what the problem could be, but it's still possible that something else is wrong in the code.