To edit permission for Create Slack Channel, View Slack Tab and Private Channel:

Step 1: Log in to JIRA Server as an administrator

Step 2: Choose Settings button at top right corner

Step 3: At drop down menu, select Issue

Step 4: At the left hand side, scroll down then choose Permission schemes option

Step 5: Click on Permissions action

Step 6: Scroll down to Create Slack Channel then select Edit link

Step 7: Add Grant Permisson pop-up, add View Slack Tab and Private Channel permission then click on Show more to view all

Step 8: Grant your wish permission then click Grant