i don't understand why when i put them burrowed under properties in scm draft that they are instead not burrowed.

Make sure the player that owns them has Burrow researched.

um k well then how do you get lurks that cant unburrow but are already burrowed lol?

create them with triggers

give to a player who has burrow disabled. You have to create them owned by a player who has it researched (lurkers don't need it researched). If you want a computer to never unburrow, make a player slot neutral and disable burrow for it.

The same goes for siege tanks.

I'm not so sure it's possible to have lurks that attack but never unburrow, because lurkers can burrow and unburrow regardless of wheather or not burrow is researched.

lurkers can't unburrow when it's disabled. If the player doesn't have it researched, they do now. Regular computer players can always unburrow units, even if it is disabled.

Oh, I didn't know that. Neat.