Using 'Show Enhanced Settings' I sharpen my vids under 'video effects' but I don't seem to be able to make the changes permanent.
How can I do this?
To be able to save the settings you need to make the adjustment in Tools > Preferences. At the bottom of that window, select 'All'. Then click the little icon to the left of Video > Filters which will drop down the list of things you can alter. Select 'Sharpen', make your adjustment and Save.
The adjustment control here is different to the way it's done in the menu that you used so I'm not sure if it does the exact same thing. Both are called Sharpen though, so you would think it would be the same.
Then click on the word 'Filters' and select the 'Sharpen video filter' and save again to (presumably) activate the sharpen filter with the adjustment you made.
Anyway, seems to me that's what's needed to make the adjustment permanent.