Normally, WordPress will remember which editor mode you were in (Visual or HTML). So if you were using the HTML editor and you save a page, you’ll be returned to the HTML editor.
If you (or your clients) would benefit from always returning to particular mode, you can set that up
add_filter( 'wp_default_editor', 'force_default_editor' );
function force_default_editor() {
//allowed: tinymce, html, test
return 'tinymce';
}
*Functionality is there but quirky in pre-3.3