Hi @selina27
Hope you are doing fine!
Updates should not change any custom CSS or formulas in the form since this information is saved in the database and the updates replaces only the current files for the plugin. Could you share more info about how the CSS and formulas were customized? Also, please help us sharing the form export so that we could review the existing settings in our lab site.
Please take a look at the following doc on how to export a form:
https://wpmudev.com/docs/wpmu-dev-plugins/forminator/#import-export
If you are concerned about any sensitive information in the form, then you can duplicate your form, remove any sensitive information, and then export it.
You can share the export file via Google Drive, Dropbox or any cloud services in the next reply.
Looking forward to your response.
Kind regards
Luis