This isn't necessarily a process that is "hard" to complete. In fact - the opposite. But there's a step in the process that's really important to pay attention to that I'll explain in a bit.
Log into the personal Facebook profile that is an admin to the page or group that is having reauthentication issues. Then go to Settings.
When you're in your Settings, go to Business Integrations. Next, scroll down your Apps list until you find CoSchedule.
Mouse over the CoSchedule app, and click the "x". Then click Remove.
Once you click Remove, our app permission will be removed from your account. Then you'll go back to your CoSchedule calendar, and connect the profile as if it is a brand new profile. Do not delete the existing connection.
For more instructions on reauthenticating your page, check out Reauthenticating Social Profiles.
Click your Profile Picture in the top-right corner of the Twitter website. A drop-down menu will open, click Settings.
Next, go to your Apps page and click Revoke Access next to CoSchedule.
Once you have revoked access, go back to your calendar and create a test message under the Twitter account that you have revoked access from. Click on the current day and make sure the Twitter message is scheduled to go out immediately.
If you revoke access, the message will automatically fail and not be posted to your Twitter account. After the message fails, go to Settings > Social Profiles and complete the reauthentication process.
After you reauthenticate, your account will be set up and will be ready to post without re-authenticating multiple times.
Log into the Instagram account that you would like to reauthenticate. Then click on the gear icon to access the settings menu. Click on the "Authorized Apps" option.
Then look for CoSchedule and click the "Revoke Access" button.
Once you have revoked access, go back to your CoSchedule calendar and create a test message under the Instagram account that you have revoked access from. Click on the current day and make sure the Instagram message is scheduled to go out immediately. The message will automatically fail. Once that happens, go to Settings > Social Profiles and complete the reauthentication process to get that Instagram account connected to CoSchedule again.