For switching from auto to manual renewel of subscriptions you will need to do the following:
Go to
https://secure.2co.com/myaccount/
Enter the email address that you used to purchase FBX to create a 2checkout account.
Once you are logged into that account, you need to go to "My Products".
There you should see your subscription and be able to enable / disable auto-renewal.
For the other issue, we'll need to take a look at your log files to check what is going on so please use the Report a Problem option on FBX's Support tab to send those to us.