When you make various changes to an App it will affect how or if it continues to work as follow:
Publish - You need to publish an App to check if all the features you have added work.
Share - once you have shared the URL with someone they can then install the App and share it with as many people as they want who can all install it and share it and so on.
Change - If you make changes to the App by adding or removing sections, images etc these are ONLY applied to any installed Apps IF you republish it. Then the changes are applied next time anyone who has installed the App opens it.
Delete - If you delete an App it will stop working on devices, even if it has been installed.
Rename - If you Rename an App, installed Apps will stop working, in the same way as when an app is deleted.
After renaming an App you will need to publish it again for it to work properly and share the new URL so your users can instal it again.
Before renaming an App you should consider how many people it may have been shared with as their version of the App will stop working if you do so.