I do have an IXUS but not the 135. I've never had a problem with it and I thought I'd take a look and see if I could shed any light upon your difficulty. I found the manual here:
http://gdlp01.c-wss.com/gds/3/030001...erGuide_EN.pdf
As far as the date stamp is concerned, according to the manual, you should have this:
If you haven't, I suspect a fault with your camera and you'll need to contact Canon.
To change the image resolution, you should have this option:
I hope this helps and I'm not treaching grandmother to suck eggs!