The level of difficulty (Alien: Isolation)

I play on maximum difficulty, only today realized that at manual the scanner indicates the direction where you want to go. I just climbed all the rooms looking for where to go, maps, level then no.
Now, when you know where to go, easier to play. But it's still difficult, ammo is hard to find.

Passed the game on Nightmare difficulty.

There were problems with the level where you had to run the reactors. Reached the moment when you need to run on bridges and turn on the reactors of the weapons I had nothing, the only thing found is a single projectile to the BOLTGUN, you can only kill one Android. Decided all androids to collect a series, that they are 4 pieces for each other went behind me, and I will deal with reactors once I did so to turn on the reactors, but when it was time to turn the last switch, there is still further away there were some androids, maybe I imagined them?
It was decided to replay the level, collecting and saving ammunition. Was thinking of using this bridge when it was necessary to go forward sprint past the androids, I will go to the basement with strangers, pawluch and come back, but these bastards can see a mile away, and slip quietly fail. Had to waste ammo and kill them all, then after a basement with strangers, I returned to these bridges reactors, and the androids were all living and go 4, and I have 7 rounds to the gun, 9 rounds shotgun, and 3(or 2) of the cartridge to the BOLTGUN. But it was enough to kill these bastards.

The rest of the game particularly difficult places do not have, except for this place. Need to conserve ammo on this level of difficulty.

Bloody Baddy wrote:
About the difficulty level in the settings you can switch at any time, it does not have to start the game again.
Where is it? Not found.