Tried three networks, all same problem

Today for the first time, and I have tried this now on three separate networking thinking it was the router, if I do a reply and strip out the text, and then write a response, and then preview that response, it takes some text from the other post and randomly selects some of the text and puts it into my current reply, and then I need to strip it all out.

I have a screenshot to illustrate this it helps, but it looks like I actually included their text right in the middle of my text, very strange. Anyone else experiencing this?

Thanks

I haven't experienced this as I never use the preview function.

Could you please post the screenshot?