For Pursed Lip Breathing, many people encourage inhales through the nose, but there's nothing wrong with inhaling by breathing through the mouth. If I'm exercising hard, I am a mouth breather; it's just natural. I do use PLB, but, I inhale through my mouth. I can't get enough air in through my nose to go at my hardest and that's the point of exercising, at least it is for me.

Hi Renee
Always Breathe in through the nose as this acts as a filter and blow out through the mouth slowly it may make you cough which is a Good thing
Take care
Eric x

My therapist says breathe them through your nose, normal speed and velocity breathe out through personal lips, a little slower and longer than the intake breath says that should help with the trapped oxygen in your lungs

You do want enough force to blow out the candles, but not enough to move them! Blowing too hard means you don't get the length of the exhale you need. It may take some time to find the appropriate count and rhythm of the exhale, inhale for you.

When walking slow it should be in through the nose and out through the mouth. But as your pace steps up or exhilaration steps up for a hill, then you will start breathing in through your mouth like an athlete dose when running.
When doing pursed lipped you exhale with force like blowing out all the candles on your birthday cake. It is how I was taught, hope it helps you like it did me.