How to change Schedule E line27 to "yes"? One of my K1 has loss carryover(of previous years), another one has gain. I want to report the loss unallowed in a prior year.

As you complete the K-1 interview you should see this screen ....

is the K-1 from a publicly traded partnership?   if so, it's passive losses can not be used to offset profits from other partnerships and the loss carryforward will not appear on form 8582.   

I'm afraid i can't report the loss carryover of company A on company B here. The loss is of A, B has a gain. I put the loss carryover on A here.

No none of them is a public trade partnership.