How to use apex:actionsupport such that it only saves the last radiobutton in repeat in Salesforce?

I build a radiobutton within a repeat of a list and then use actionsupport with event set to "onchange".

Example,
<apex:outputPanel id="repeating">
<apex:repeat value="{!change}" var="c">
<apex:selectRadio value="{!save}">
<apex:selectOption itemValue="{!c}" itemLabel="{!c}" />
</apex:selectRadio>
</apex:repeat>
<apex:actionSupport event="onchange" reRender="repeating" action="{!saveInformation}">
</outputPanel>

However, this code only work on the final/last button. What I wanted it to do is to be able to save more than 1 button and any button that is changed. My current code only work on example;

button 1 *when pressed, nothing happen*
button 2 *when pressed, nothing happen*
button 3 *when pressed, this button can be saved*

I wish it to be able to save any pressed buttons and also able to take more than 1 buttons to save.

Is there a way to alter my code or should I make any changes?