No the app will not work on theme change.
You need to add the below code above </head> in your theme.liquid file to get the app working.

{% if template contains 'product' %}
<link rel="amphtml" href="//{{shop.domain}}/apps/fireamp/products/{{product.handle}}" >
{% endif %}
{% if template contains 'collection' %}
{% assign collectionpageurl = content_for_header| split:'"pageurl":"' | last | split:'"' | first %}
{% assign collectionHandle = collectionpageurl | split : "collections\/" | last %}
{% if collectionpageurl contains '?' or collectionHandle contains '/' %}
{% else %}
<link rel="amphtml" href="//{{shop.domain}}/apps/fireamp/collections/{{collection.handle}}" >
{% endif %}
{% endif %}
{% if template contains 'blog' %}
<link rel="amphtml" href="//{{shop.domain}}/apps/fireamp/blogs/{{blog.handle}}" >
{% endif %}
{% if template contains 'article' %}
<link rel="amphtml" href="//{{shop.domain}}/apps/fireamp/blogs/{{article.handle}}" >
{% endif %}

If you are not able to add the code yourself, you can mail us at "support@mlveda.com" and we will get the app working within 24 hours.

Updated on: 05 / 13 / 2020