If you want to update to the new version of the theme, pls make sure that you did not change anything of the default theme (such as you did not add the CSS Code to change the default layout, functions, ...) => go to Themes > activate the default theme of WP >> delete the old version of the Boutique theme >> download and upload the newest version of the Boutique theme and activate it again. Your site will be in the latest version
In case you changed or added something that is different from the default style of our theme, you should back up everything you added before. Then update the theme as all steps above. After updating the theme successfully, you can add back all the things you backed up.
However, you should write the changes in the Child theme. It will not affect the main theme when you update. And it's safe for you. We also do not support customized sites.
Hope that it's useful for you.