1.   A dark glue, such as some waterproof glues, will usually leave a dark thin line on light-colored wood.

2.   Here, you will have to switch to a waterproof glue, like epoxy resin.

3.   I am using Titebond waterproof glue.

4.   Small holes can sometimes be filled with quick-drying waterproof glue.

5.   The difference between regular and exterior plywood is that the exterior plywood is glued with a waterproof glue.