Something to bark at

Sometimes I'm timid on my walks, but I'm becoming more confident. If there's a person walking (or running) without a dog then I will generally bark and raise my hackles. The person usually looks scared, which is satisfying, but my owner gets very cross. All a bit confusing. 

Today I barked and chased two running people with headtorches in the morning, and this afternoon I did the same to a woman who had two walking poles. 

My owner says I will get a reputation.