first run
Run it on one selected note.
1. Open the Piano Roll
Open a MIDI part in the editor and make sure the notes you want to affect are visible.
2. Select the reference note
Click one note at the beat position you want to match. The selected note is the reference point for the command.
3. Run one mode
Use your assigned shortcut. All Notes selects every note at the same beat position. Same Pitch Any keeps the pitch filter. Same Pitch Exact matches the selected pitch set.
4. Edit normally
Once the matching notes are selected, use normal Studio One editing: velocity, length, mute, delete, transpose, or any command you already use.
Fast sanity check
Make a four-bar MIDI clip with one repeated kick or hat. Select the first hit, run All Notes, and confirm the matching hits in the later bars are selected.