Welcome to the Community, info1321.
In QuickBooks Online (QBO), we're unable to make all customers active at the same time. You'll need to do it one at a time.
Find out more about changing customer status in QBO through this article: Make a customer inactive and then active.
I know how this feature provides more convenience to you and other users who are working on a large number of customers. In the meantime, I encourage you to visit our QuickBooks blog. From there we share the latest QuickBooks news and feature updates of the product.
You might also be interested in learning more about managing customer list: Manage your customer list.
Stay tuned for updates. Drop me a reply below if there's anything I can help you with. Wishing you all the best!