Hello, thebard.

This question has been asked before. You can find this question, and hopefully the solution, here: https://support.mozilla.org/nl/questions/1003390

If not, please leave a reply.

Sorry, way above my head, only a novice. I need a dummies, step-by-step guide!

thebard said

I have version 45.5.1 and Windows 10. After numerous problems with freezing etc I want to un-and re-install without losing all my emails and data.

Then do it. The very technical answer is "there is nothing stopping you, just do it and it will still be there". This is not a Microsoft product.

? No it is a mozilla product, which is why I asked the question on the mozilla forum!