I have  menu item that points at a item. when you go to the menu item on teh front end the item title is shown as a H2, i would like to change thsi to H1.Ideas?Ww

The H1 is used for the page title usually, so that is why the item title has H2. If you don't ever use the page title inside the items then you should change it to H1.

The first thing you need to do is a template override of k2 template, if not already. (It is actually a copy of the contents of the template folder in components/com_k2/templates to templates/your template/html/com_k2).

You need to modify the item.php file in templates/your template/html/com_k2/default/.

I've changed line 46. It works, but now the validation doesn't pass:
1
end tag for element "h2" which is not open

2
end tag for "h1" omitted, but OMITTAG NO was specified

3
start tag was here
Any other files that need a change? We like to have our content clean.. Kind Regards, Dennis

Just make sure that the tags of h1 and h2 open and close correctly.