Thanks for the topic.
1. Could you, please, provide us with temporary wp-admin access so we can take a closer look?
2. Theme Options > General > Header Settings > Top bar text color > Dark.
3. Provide us with FTP access.
Please read our documentation – https://xstore.helpscoutdocs.com/article/37-plugins-update
3. You use latest theme version but the version of XStore Core plugin is old. Go to Appearance > Install Plugins > 8theme Core > click update.
If after the update the problem won’t be solved, we need FTP access to check the problem more deeply.
4. I’ve updated WPBakery Page Builder.