tombow liquid glue

Highly recommended Tombow glue.   There are two tips - a fine tip and a wide tip (the latter for large areas).   Acid free, photo proof and washable.   It is repositionable glue. 

to reposition apply a thin layer of glue and leave till it dries.  Then press the second layer and reposition if necessary. 

If permanent then simply apply the second layer immediately and wait till it dries!