Dad can be very soft-spoken. This often makes it difficult to hear what he is saying. Dad is aware of this. Don’t hesitate to ask him to repeat his words or raise his voice a little.
Dad often has difficulty finding the right words, uses incorrect words, struggles to recall names/places, omits key details, or loses his train of thought in general. This can be exacerbated by tiredness, sleepiness, dehydration, busy/noisy environments, etc. Asking him to describe who/what he is thinking of can sometimes help.
Do not take all complaints at face value. While there are many things that Regis needs to improve on, almost all people who experience the kind of dementia, hallucinations, and loss of independence that Dad has, develop some form of paranoia. In addition, Dad is not used to sharing accommodation, has certain preferences that Regis can’t always accommodate, and still has an ego like anyone else.