Sorry about that demo video. I was in a hurry and grabbed it quick. I should have referred you to this!

https://www.youtube.com/watch?v=eus1hMD_eUo&t=283s

Kenny explains "Track Timebase - Tempo in REAPER". This is actually more simple than it looks. There are only a couple options so you can just try them until you get what you want.

By the way, Kenny Gioia is a Incredible Reaper Resouce. He makes hundreds of these videos to explain every item, detail and feature in Reaper. He updates his videos as new features are added. You can actually contract him for zoom sessions to hold your hand and walk you through sessions if needed.

I can only assume S1 has similar features to permit adjusting timebases as shown in the video. Does S1 have a Kenny?

BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6