Narrowing down a topic can be difficult. I provide dissertation coaching and offer feedback on proposal drafts for doctoral candidates. You will have to potentially eat, breathe, and sleep this topic for a period of time. I always advise students to pick a topic that is the most interesting to them. When you wake up in the morning, what topic motivates you to get out of bed? When you go to bed at night, what topic do you feel good about pursuing?
Once you narrow down some topics that truly motivate and inspire you, I suggest that you conduct a brief literature review to see what other researchers have written on the topic. Conducting a literature review can assist you in narrowing your topic, determining your angle/position on a particular topic based on what is missing from the literature, and help you critically identify how your project can fill in the gaps in the knowledge about your topic. Please share your thoughts.