I am trying to shift+r on the arrow but nothing changes. I tried changing the mod controls, but that does not fix it. I tried it with different game and mod versions but nothing seems to fix it. pls help :(

I haven't seen this problem before, so please help me diagnose it by following my instructions and telling me what happens. If you research fluid connections and then build a fluid connection from pipes, can you change the settings (direction, increase, decrease) of the blue diamond/arrow that appears?

I don't even have a blue arrow, weird. I'm using Factorio version 0.16.35, and the latest mod version.

Okay, it turns out that I connected the pipes the other way around. Anyways, I still can't change the anything on them.

Hm. Does it work in a different world? Does it work with fewer mods? Try disabling your mods some at a time and retesting to find out if there's another mod causing this.

It does work in a different world.