Should I put instructions like 'explain things to me as a beginner' into my organization/global custom instructions so they apply every time?

Yes — general preferences about your experience level, how you want things explained, and how you want the AI to guide you between tools can be placed in custom/organization-level instructions (referred to in the discussion as a global Claude MD file) so they persist across all conversations rather than needing to be repeated each time. One participant described going further: having Claude research them online and analyze their writing style from emails, then saving that profile so every output is contextualized to how they communicate. Beyond the global file, you can also create Claude MD files scoped to specific folders or projects (e.g., a client's bookkeeping cleanup) that layer more specific instructions on top of the global ones. One participant described a full structure: firm-level instructions, then client-level folders each with their own Claude MD file and relevant skills tailored to the type of work done for that client.