Thank you...but File/Transcode Settings... is greyed
Select the asset, not the timeline. Right click, you should be able to pick a transcode setting. If not, you are probably trying to set it on an asset that is transcoded already. "Revert to original," then try again.
Anyway, after selecting my preset, the size is always the same.
If you succeed in selecting your preset for the asset, and the size does not change, please a) post a screenshot of your timeline panel where we can see both DVD and BD transcode status, etc and b) list the preset specs you are using.