Can I change things after deploying the app?

Hi! I am developing an app for our homeless ministry and I would like the board to See the app in action with putting in non-sensitive information/fake clients before we commit to the Core subscription and do usernames and all of that. If I deploy today, would that mean I could not go back and make those changes like requiring subscription, etc? We will NEED the security of this information if we do decide to use this full time. We are a non-profit, so I am giving a donation for this for us to try to keep track of the resources we give to clients and the ones that call our hotline. I am afraid if I deploy now, I will have to do all the work AGAIN and do a whole new app and redeploy with the security features and confuse all the older users Im already trying to convince how much easier and user friendly this will be.
Also, if we decide that my initial spreadsheet/intake questionairre needs extra info, can I change those columns and add those things after deployment without interrupting the app and losing contacts if and when we do begin adding data?? (For instance, if I upload as many current clients as we have and then we decide we want to add a column that shows where this unsheltered person usually sleeps location wise, could I easily add that into the spreadsheet and integrate it into the app without having to start all over and losing progress?)

I just developed and deployed an app for the company I work in and am running into a similar situation. 1 recommendation I can give, is to copy the app and leave one as the beta tester and another as the continuing work of the app as the official version. Also, I believe you can change the version name within appsheet and edit based on that, all changes will not reflect on the app until it is updated, like any other app in the Play Store

You can update the app after it is deployed. For example, in your example if “we decide we want to add a column that shows where this unsheltered person usually sleeps location wise, could I easily add that into the spreadsheet and integrate it into the app without having to start all over and losing progress” you could easily add this by pausing the app, adding the column to your spreadsheet, and then regenerating the schema in appsheet to update the columns.

Obviously larger changes pose more consideration, but if you are just tweaking based on testing, it shouldn’t pose a problem. However, you do not need to deploy the app for people to test as long as it is a small number. You just will lose some features like automated emails.