> Anyway, some people don't like "dark matter" and prefer to change the theories

It seems a bit more complicated than that, mostly because the vulgarization often available too is quite bad to explain the issue.

My understanding:

- Our current theories fail to predict/match an array of observations, as if more matter than what we can detect exist. Some scientists called that the "dark matter problem", that's what most physicists working on the subject refer to when they talk about "dark matter".

- Every theory you talked about: dark matter big objects, dark matter particles AND the "change the theories" (i guess you talk about the Modified Newtonian dynamics, where you alter Newton's second law at low speed to match some observations) are dark matter theories: theories that tries to explain why the universe act as it is, not matching our current theories, either by adding new things, or by modifying our discovered laws to match our observations. Each of those theories have multiple branch investigated.

- the "dark matter particle theory" is sometime vulgarized as "dark matter" on podcasts or in books/articles. This is because more scientists work on particle physics than on gravity or astrophysics (my country present like 3 astrophysics thesis each year, and dozens of particle physics thesis). I think this caused a huge misunderstanding.

- Some people with a common understanding (like mine, i meant non-physicists, it's absolutely not derogatory) like MOND because philosophically it is quite nice, and also tend to draw in people with minority/anti-etablishment habitus[0] (cf: most physicists working on those subjects are particle physicists). I'm not saying this theory is worse than the others at all, i'm just saying that the kind of layperson drawn to it can be _really_ sure they're right and profess their beliefs everywhere, and sometime claim that "MOND isn't dark matter", when they really confuse dark matter as a problem to be solved with "dark matter particle theory". Misunderstanding happen to everyone btw, it's really not a big issue.

In case you did not talk about MOND but about theories that claim that the issue are with our tools to observe at a distance, some theories include that to explain some of the inconsistencies, never all of them, and those theories seems to really be a minority atm, so hopefull it wasn't about that.

[0] Also, those habitus seems to draw in grifters who know they can make quick bucks by selling books/conferences if they look convincing enough, which is why MOND has a weird reputation now, but absolutely serious physicists and mathematicians work on the subject very, very seriously.