Prices apear not right in shop after change vat

Hello,

I have frontstore-woocommerce on a microsoft IIS server.
I have my prices set when the tax was on 21% + 6% So, that was wrong, I had to remove the 6% becouse the were calculating to 27. But now, the prices in my shop are 6% to less.
I have tried the caching stuff.
That is not working. When I am in my backend the prices display right. in my admin and also in the shop, but customers do not see the right price.
I have no clue how to fix this and were to look.
Does somebody know the solution?

Kind regards,
Femke