If you’d like to move a single candidate from one campaign to another, go to their candidate profile (you can use the search at the top to make this easier), then click on the campaign options menu (the 3 dots in the upper right corner of the campaign.) Then click “Add to new campaign” in the upper right corner of the candidate profile and select the new campaign.
If you’d like to bulk move a group of candidates from a campaign to another, you can use the Network tab to filter the candidate group and move them to a new campaign.
To do this, go to the Network tab, then select the campaign name under the “Campaigns” dropdown. Then, use the "Campaign Engagement” filter to select the specific group of candidates you’d like to move. For example, if you’re trying to move all candidates who have never been contacted (e.g. those that are still in “Needs Review”) while ignoring the candidates who have already responded, select “Never been contacted”:
The Network Tab is also an excellent place to consider starting a re-engagement campaign with candidates who perhaps "opened any message but never replied," etc.