moeen1368,
It depends on when and where the design rules were setup (these are default prior to the project being imported). If you've adjusted the settings in PCB properties after the import, they don't have any effect and you'll need to adjust the settings in the 'Spreadsheet' view at the bottom of Ultiboard.
A best practice is to adjust the trace width / spacings in the 'Spreadsheet' view at all times.
The Autorouter should definitely follow these rules (if not please report back and let us know if you have any problems). Also check for any special 'group' settings (in the event you've grouped nets together to have special rules for the group, such as a bus or diff pair, etc...)
There are also some 'best practices' for the Autorouter and routing in general. I think they've been discussed in the forums previously.
Regards,
Pat Noonan
National Instruments