I sold my soul to the devil years ago and use Chrome, except for key areas where I need to know that the latest security patches have been applied, and in those cases I use Mozilla (more out of superstition than anything else, admittedly). Historically, IE was always full of security holes, but I don't know anything about recent versions and have the new version on my laptop, which I don't use for anything critical.
How old is your dsis, MI? I was diagnosed with anorexia in 1978. But that was because my dm recognised it very quickly and so did the GP (in rural Dorset, I might add). Not that this equipped dm well for dealing with it. But that is a whole 'nother story. It got recognised all right, but no one I had access to knew how to treat it.
As for stress in schools being responsible for the rise in MH probs among today's teens - I am not so sure. I think the change in the education system has certainly played a part, but the internet and the 24/7 communication culture is also incredibly pressurising and generates a lot of misery. I think the damage done via always-on social media is a lot more than people realise, even where teens are only passive consumers. I am currently still on my FB 'fast' and it's giving me a different perspective on certain aspects of how I use the internet. I was a late adopter of FB as I strongly disapproved of it (for various, possibly peculiar, reasons), and only joined because I had promised dd she could join when she was 13 and I wanted to be there to keep an eye on what she was up to. It grew on me, and I used it for work. But I may be coming round to being a Luddite again. I deleted my LinkedIn account 3 years ago and my life didn't end. I've never used Twitter and never will. I don't think being on FB (or any other social media thing) has ever done dd any good.
Monty, dd is not too good at the mo'. She is struggling to keep her head above water, but it's hard to know what to do. Also dh is still prone to gnashing his teeth about what he thinks she is/isn't doing and ds is furious that she's here because he wants her room. I am getting through the days and ignoring the feckers as much as I can.