Campaign send hours you can edit live on Settings → Schedule, not on the sender panel. Exclusions on the same Settings tab skip leads already touched. Open enroll preview before you enroll so skipped counts are not a surprise.
Open Settings
Open the campaign.
Select the Settings tab.
Use the four sections: Audience, Senders, Schedule, Exclusions.
Audience picks the person list. Senders picks who sends. Schedule holds the hours you edit. Exclusions holds the three skip rules.
After launch, Settings may lock senders, schedule, and exclusions until you select Edit campaign. You can still enroll leads.
Schedule
Open Settings → Schedule.
Set start date, end date, timezone, send hours, and active days.
Save.
These hours are the ones customers edit. The sender default window is 9 to 18 in the sender timezone. That default is not a control on the sender panel. Account Protection still blocks sends outside the sender window.
Exclusions
Open Settings → Exclusions.
Turn on the rules you want:
"Exclude leads contacted in other campaigns"
"Exclude leads messaged by other senders"
"Exclude leads contacted by same sender in other campaigns"
Save, then open enroll preview before you enroll.
Enroll preview is the check that the three rules did what you meant. Open it before you enroll so the skip count is not a surprise.