I have in my CustomTheme a default.xml file. I tried to get the xml to work and used some of the samples I found here on StackExchange. Non of them are working for me? 
So apparently I have done something wrong or something else is interfering the xml file to be applied.

My default.xml resides in:

app/design/frontend///Magento\_Theme/layout/default.xml 

I cleared all cache, static files, the files in the /var and run setup:static-content:deploy 

But nothing appears! 

I tried several things like removing the footer links, and moving the shopping card like in this post:[Magento 2 Block/Element order](https://magento.stackexchange.com/questions/117958/magento-2-block-element-order?rq=1) This is my latest trial default.xml the block is prepared in the cms\_block.
Using Magento 2.1.2 

```
<?xml version="1.0" encoding="UTF-8"?>
<!--
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
-->

<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <body>
        <referenceBlock name="footer">
            <block class="Magento\Cms\Block\Block" name="footer_social_links_block">
            <arguments>
                <argument name="block_id" xsi:type="string" translate="true">dth_footer_social_links</argument>
            </arguments>
            </block>
        </referenceBlock>        
 </body>
</page>

```