Change select value when changing another select

I got 3 array's where from i make 2 select box and a checkbox. What i want to do is that when i change CMS the checkbox value needs to change like in the array.

if i choose Joomla in the select box than i want the checkbox that is made with the $aOnderdelen, than in the array $aOnderdelen i have an array with Contact-form Foto-gallery and Carousel and this 3 have an array with the name of each CMS with different values and this are the values that the checkbox needs to get when you choose one of those and the CMS.

Example: i choose Joomla and i choose a Contact-formulier than contact-formulier checbox gets 3 as value.

$aCMS = array('SilverbeeCMS','Joomla','WP','Drupal','Scott');

$prijsPerUur=1;
$basisPrijs=
array(
    array('titel' => 'Kopie', 'uur' => '8'),
    array('titel' => 'Maatwerk', 'uur' => '10'),
    array('titel' => 'Aangekocht', 'uur' => '12'),
    array('titel' => 'Custom', 'uur' => '14')
     );

$aOnderdelen = array
(
    'Contact-formulier' => array 
        (
            'SilverbeeCMS'=>3,
            'WP'=>2,
            'Joomla'=>3,
            'Drupal'=>4,
            'Scott'=> 5
        ),
    'Foto-gallery' => array
        (
            'SilverbeeCMS'=>1,
            'WP' => 3,
            'Joomla'=> 4,
            'Drupal'=> 5,
            'Scott'=> 6
        ),
    'Carousel' => array
        (
            'SilverbeeCMS'=>1,
            'WP' => 4,
            'Joomla'=> 5,
            'Drupal'=> 6,
            'Scott'=> 7
        )
);

    ?>

This is the HTML form where the Select and checkbox are

<form action="" method="post">
                     <div class="col-xs-6">
                         <select id="cms" 
                                class="form-control"  
                                name="cms">
                            <?php foreach($aCMS as $key => $value): ?>
                            <option value="<?php echo strtolower($aCMS[$key]); ?>"> 
                                <?php echo $aCMS[$key]; ?>
                            </option>
                            <?php endforeach; ?>                          
                        </select>    
                    </div>

                     <div class="template col-xs-12"> 
                        <label><?php echo $template.$verplicht; ?></label>
                     </div>
                     <div class="col-xs-6">
                         <select id="templates" 
                                class="form-control"  
                                name="templates">
                            <?php foreach($basisPrijs as $key => $value): ?>
                            <option value="<?php echo $basisPrijs[$key]["uur"]; ?>">
                                <?php echo $basisPrijs[$key]["titel"]; ?>
                            </option>
                            <?php endforeach; ?>                          
                        </select>    
                    </div> 

                    <div class="col-xs-12"><h4><?php echo $oTitel; ?></h4></div>
                <div class="checkbox col-xs-12">
                    <div class="row">
                        <div class="col-xs-12">
                 <?php foreach($aCMS as $cmsKey => $cmsValue) ?>            
                 <?php foreach($aOnderdelen as $key => $value)
                    :
                            foreach($value as $key1 => $value1)
                            {};
                    $i++;
                           echo "<div class='checkbox'>
                           <label><input class='check".$i."' type='checkbox' value='".strtolower($key)."' 
                           name='".$key."'>"
                           .$key."</label></div>"
                    ;endforeach;?> 
                        </div>

                    </div>
                </div>
                </form>