Hello Bill,
In my earlier years I used to use a rig glue just for extra assurance, it was pretty much like superglue in a different tube and I eventually came to the conclusion that it was making the knot brittle once it had set.
Far better imo to take more time tying the knot in the first place as there really shouldn't be a need to glue knots if they are tied properly from the off.
There's plenty of choice but the tucked half blood knot is as good as any.
If knots have been failing it's often a case that the line has been damaged upon tightening, when tying.