How to replace phtml files in Magento 2.0?
<p>In Magento 2.0 admin panel (Store>Cofiguration>Developer>Debug) I have set "Enabled Template Path Hints for Storefront" to "Yes". That provides me with references to the phtml files that generates the HTML code for each section.</p>

<p>Q1) Making changes in these files gives the result I am after. But I figure they will be restored/changed if I decide to update Magento to a newer version. Am I right?</p>

<p>Q2) Is there a way to change the phtml files in another way placing the phtml files in my theme folder? If so, where do I place them?</p>

<p>(I am no big fan of XML for simple HTML changes, if possible I would like to write static HTML as much as possible. I have activated my own theme without any base theme. I am new to Magento.)</p>

<p>Thanks!</p>