Sorry about that - we know its a nuisance but luckily its super easy to fix.
Our loupes are half the weight of any other brand but occasionally they can slip down your nose at the higher magnifications.
The best thing to do is to take your Loupes to a local optician - they will heat the frame earpieces and bend them around your ears to stop them dropping down your nose. This modification combined with use of the 100% cotton head-strap should solve the issue.
Generally speaking this service provided by opticians will not be charged for.