Well I recently got burrow, and i'm wondering if it makes a difference if I use it Strong, Medium, or Weak. I only have this one ability that I use right now, so I just put it on Strong, but does it accually matter?
It doesn't matter any more. In the past you would use less MP if you use a weak or medium in stead of strong. and while some attack were less effective (like the healing abilities)when you used weak some had the same effect ( like life drain and burrow)
Alright, now you have confused me further...Can somebody put it in dumb people terms?
In the past using weak/medium/strong for burrow/sink really made differences.
Now it has changed, so whatever you choose, it will always consume 39% of the power.
Alrighty, that makes sense to me now

When I use burrow on strong in 1-player, it blocks all the icons but still gives me some damage when no dark or light icons were used. The damage was insignificant, maybe 1 or 2 damage. Is it a new thing with burrow or is it a repeated glitch?
Burrow is only supposed to block 97.5% of icons, so 1 or 2 damage should be expected.
Actually, what happens is, Burrow at 40% blocks 100% of icons, but since you can only use it at 39%, it only blocks 97.5%.
Power Manipulation doesn't work in 1P.
In 2P, if you use Burrow and Sink on Medium or Low it will affect the efficiency and effectiveness of the ability. Same thing occurs with Regeneration and Restore, which is why manipulating power for those type of abilities are not recommended. There are several cases in which power manipulation will be successful or will not. I made a few posts on some boards in the Battledome Article Section regarding it. Not too complicated to understand really.