On: every psalm and song in the daily prayers uses today’s English. Off: all of them use the older “thee and thou”. Until you choose, the Songs of Zechariah, Mary and Simeon use today’s English, as most churches sing them. The Lord’s Prayer and the prayers for the dying show the form most people learned.
The parts of the liturgy that change with the day: the appointed readings, the psalm, the prayer of the day, and the seasonal colour. Set by the lectionary rather than chosen weekly.
In Worship — The liturgy, the daily office, and the furniture of a service.