If you are referring to creating a Sandbox inside your QuickBooks Online (QBO) account, then we have a separate and dedicated forum that handles Sandbox concerns. You can find it in the Intuit Developer Community. Just hover your mouse over API Docs & Tools at the top right corner, highlight QuickBooks Online, and then choose Sandbox.Here's also a direct link: https://developer.intuit.com/v2/ui#/sandbox.
Just in case you have questions about Sandbox, just follow the steps below to post it: