E2E in security

We are seeing a different behavior sometimes. Moderator is not able to enable E2E sometimes as its not visible and only set password is visible . Sometimes we are able to view encyption option. Any guidance when this is visible. AM i missing something

First a bit of nitpicking: what you are meaning is E2EE. E2E means End to End.
Now, E2EE depends on insertable streams support in the client. Only the Electron client has builtin support for it currently. For Chrome browsers use chrome://flags and enable experimental web features.