It's hard to say why a search engine might think that was your homepage to begin with - it could have been something to do with your old website. From what I can see, zilvertron.com appears to be your homepage for the Dutch language, and zilvertron.com/home-en/ for the English language.
You don't appear to have implemented the hreflang attribute, which helps search engines to understand when there are multiple versions of the same homepage.
When you say you are "checking SEO stats on the internet", are you using an English language search engine to do so? If so, then it makes sense that it would return the English language page, as this is what is most relevant to a user searching on that engine. Perhaps this is also an association that Search Console is making?
If you search on google.nl then the zilvertron.com site is the one that appears.
You can set international targeting in Search Console, which may help. More info here: https://support.google.com/webmasters/answer/6059209?hl=en
You can read Google's guidelines for multi-lingual sites here: https://support.google.com/webmasters/answer/182192?hl=en