Changing the research advances with the editor does NOT work.
It only marks the tech as 'known', it doesn't make any other changes to the scenario file.
There is a very awkward way around it
0 Remember to make backups of all the files you are changing.
1 Make the research changes you want using the editor and save the scenario with a temporary name
2 Open the file you created in Notepad and find the country
you made the changes to (search for 'country = tag' )
3 In the country definition you should find two or three parameters named techapps, techlevels and (maybe) deactivate
4 open the .inc file for the country/scenario you want to modify
(if you want to play as the Germans in the 'road to war' scenario, look for 'germany.inc in the 1936 folder)
5 in the inc file you should find the same two or three parameters.
now copy the lines from your temp scenario and paste it over the
existing ones in the .inc file and your are done!
NOTE! . this will only work if you are using the original scenario file
it will NOT work with a scenario created in the editor