The 100% what you are seeing is not editable it just shows you the speed.
You change speed on the timeline by dragging the line up or down.
The help is hopeless, they removed all screenshots.
This is an older tutorial but still valid.
https://motionarray.com/learn/premiere-pro/premiere-pro-speed-ramping-tutorial/?utm_source=google&utm_medium=cpc&utm_campaign=13626333289&utm_content=121323657502&utm_term=premiere%20pro%20presets&keyword=premiere%20pro%20presets&ad=583435329787&matchtype=p&device=c
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