The "Deus in adjutorium" tone never changes for compline, nor for the "little hours" (Prime, Terce, Sext & None) except for Terce if it is followed by Pontifical Mass. The TONUS FESTIVUS, which is the one used generally for Sunday vespers is only used for Vespers, Lauds and Mattins. The TONUS SOLEMNIOR is only used for Vespers. The easiest place to find these rubrics is on page 112 of the Liber Usualis, under the title- "Cantus Ordinarii Officii"- Toni Communes/ In principio horarum. Hope that helps!
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