Hi, and welcome to PT!

I agree with everyone else, spay and neuter is the way to go! Alot of vets neuter as early as 8 weeks, so both of your dogs are at a good time to do it. Especially the female, since she probably hasn't hit her first heat cycle yet.

It is a myth that the personality of a dog changes. It is very minimal. the dog might become clamer and less active (A reason that some become overweight -- the owner notices the decrease in energy and makes the mistake of not exersising it well enough).

Spaying and neutering is also the healthiest thing to do. Cuts down cancer risks sooooo much.