I can't figure out how to set my default zap amount. It seems to change depending on the protocol that I'm on.
I think that's a thing of clients, not Alby. Which client are you using? In Amethyst you can long-press the zap button to configure zap amounts and other settings.
I use Alby on desktop with Primal and Snort so I can't long press. With WOS on my mobile using Amethyst everything is fine but most of my social media time is at work on my desktop.