Minecraft – how would i summon an armor stand holding out his hands facing east in 1.11

In order to increment by 1 anytime a player dies, the objective must be type deathCount. Something like this would work:

/scoreboard objectives add deaths deathCount Deaths

If you're making dummy objectives, you're using a similar command except with "dummy" in place of "deathCount." A dummy objective can only be changed with the following commands:

/scoreboard players add (player) (objective) (value)

/scoreboard players remove (player) (objective) (value), and

/scoreboard players set (player) (objective) (value)

What I would do is summon another ArmorStand under and increment all existing ones within certain range, maybe just those that have same X and Y coordinates. That way it would not interfere with other existing goalposts.

Alternatively, once you reach ground, lock all existing goalposts (by using another scoreboard objective). When you create new goalpost, you could again summon ArmorStands under and increment the score for those that are not locked yet.