The reason its turning white is one or both of the following:

1) Your scalp is sweating or getting wet before the glue has actually dried.
Officially, this can be 24 hours, but certainly within the first few hours of applying glue you need to keep your head cool.

2) You're applying the glue too thickly and not allowing enough time between coats.
A couple of thin coats spread evenly are MUCH better than 1 thick coat.

The best white glue (in my opinion) is Oil Resistant White Glue (ORWG) but even this will not remain clear if either/both of the above happens.