Change text in default form fields

Using the boldy template for my website, I do not succeed to change the default text that is displayed in the quick form on the site (ie homepage). I would like to change Your name, your mail and your message into Dutch language.

I did manage to change the confirmation message, but the default settings remain English although I changed the text on a few places allready. Where should I change these labels?

https://www.contentcreaties.nl