@igm,
1.
Nothing is not any single being.
This means that if you take no matter which particular being in isolation, that being will not be a nonbeing.
2.
Nothing is not every single being.
This means that if you take all particular beings one by one, each one of those beings will not be a nonbeing.
3.
Not any single being is not every single being.
This means that you cannot find
even one particular being that is
not each one of all particular beings. Why? Because nothing is
both "not any single being" and "not every single being," so these two expressions are equivalent.
4.
Any being is any other being.
This is just a (positive and simplified) rephrasing of the third sentence.