What steps to follow to alter 4:3 to 16:9 ?

Hi,
I had SD 720 x 576 footage that was 16:9 but somehow in quickstream fixing it in videoredo its gone to 4:3, and plays at 4:3, MediaInfo reports it as now 4:3.
I have deleted the originals not realising this has happened, how best can I undistort and make 16:9 again the video ?
Its still 720x576 as it was when 16:9, being SD footage, just somehow the pixel ratio has got messed up.

Totally new to DaVinci 16 so please talk me through step by step what to select, as I havent a clue what settings are where.

Thanks

DBenz

Right click on footage and Clip Attributes. Change aspect to 16x9.

Hi,
So i place the video into the timeline, right click it select clip attributes select 16:9 then export footage, and i need to find out how to do export, and also as .mp4 , as file size will be smaller, as that going in was .mpg and a bit large for fitting onto a dvd.

and hey presto its 16:9 again.

thanks
DBenz003