I'm trying to disable the "Right click armor" option on the server, but it still works.

I want to disable it as players can steal armor from the GUIs.

I am changing the server config from /config/quark-common.toml

I have already tried restarting

Minecraft version: 1.16.5
Quark version: Quark-r2.4-309

The “right click armor” option is actually a client side feature and cannot be disabled by the server. Perhaps try using a different plugin for the guis or use an anticheat that does not allow for stealing from it. Alternatively, you can also make the armor in the gui undesirable, such as by having curse of binding and vanishing and negative enchantment values and stats, or by getting rid of the armor in the gui entirely.