I started with an MP4 at about 1.7gb in size and then removed the adverts. I then exported the edited file and it came out at like 6gb. What am i doing wrong as I expected the finished file to be less than the original 1.7gb. I did not export it as a high quality HD file.
Was the source file downloaded from the Internet or recorded from a streamed source eg Netflix, live TV etc?
Without more detailed information on the source file - you can use MediaInfo to analyse the file and post the results from the Tree view - I would suspect the source mp4 is probably highly compressed and the export setting you have used - you did not indicate which preset option you selected - resulted in a less compressed file, hence the larger file size.