Dictation Annoyance

I’ve changed over to dictation and voice control on my Mac to enter text into scrivener. It works fairly well, but tends to insert random words. Sentences often begin with ‘I’ or ‘And’ when I haven’t used either word, and sometimes whole phrases get pasted in, something that I typed four chapters ago. Is this normal, is there any way to adjust it. It’s not fatal, but certainly annoying. It seems to happen much more often in scrivener then it does anywhere else. The voice recognition also seems to be of a better quality when I’m not in scrivener. Any thoughts from anyone on this would be appreciated.