Performance -> Caching
In general, yes, the form should update with the values you set.  However, there are few different ways you can override form settings.

The two in question are cache and block_cache.  You need to search the files for lines that look like:

$conf['cache'] = FALSE;
$conf['block_cache'] = FALSE;


The integer 0 or the string '0' or "0" may be used instead.  Checking the settings.php for the site, and any custom modules.