Key answer
Specify the output affected, when the exception ends and which rule resumes. “More playful this time” could mean one reply or the whole document; “only the opening paragraph of version two” is easier to check.
Full explanation
For example:
Keep the lasting default concise and plain. Use exaggerated humor only for this poster's three headlines; keep the body unchanged in style. Resume the default after delivering those headlines. Do not update lasting account/project preferences.
The target is three headlines, the end is delivery, and the retained rule covers body/future replies. This defines scope. For a whole activity, say so; do not repeat every preference each turn.
Multi-turn rule changes deserve checking. The 2026 SEQUOR preprint tested ten open-weight models and Gemini 3.1 Flash Lite over 50-turn simulated conversations, comparing retained, accumulated and replaced constraints. Compliance declined with length and could recover temporarily after replacement. Check the currently effective rules each turn. Sections 3–4
Distinguish temporary conversational agreements from saved product settings. Claude says account instructions apply across conversations and project instructions within their project. Saving one-off humor at account level broadens its scope. Personalization documentation Put temporary requirements in the task; change lasting settings only for lasting preferences.
If a later reply keeps the expired style, clarify scope: “The humor exception ended; resume the default here.” If it entered settings or memory, inspect and edit there. Whether a new chat is affected depends on those settings' continued applicability.
Check both the current output's limited exception and later return to default; verbal agreement alone is insufficient.