Twenty twelve view in mobile

I have 3 sites using twenty twelve.

2 of these sites when viewed on a mobile phone show up in a list style view and the 3rd site shows up pretty close to what it looks like on a desktop.

Why do 2 of the sites show up as a list style.. by list style I mean when you go to the site on a phone, it just shows a list of my posts. To make things worse, the date it shows for each post is 1970 for some reason??

A few weeks ago when I check the sites on a phone all 3 showed up normal as if you were on a desktop, now all of a sudden 2 of them are list styled.

Can anyone tell me why this is and how I can get them to not show up as a list???

Thank you