How to re-attach scalp??

Hello! I have no idea how to make this piece reliably stay on my Zuora and it's terribly annoying for it to fall out all the time. I hardly touch her because of it and I just know there has to be a solution but what? Or is there an easily dissolvable glue to use for a semi permanent fix in case I ever need to open her head again, but will keep it on until then?