Hi Lynette,
If you change your subscription from 'Microsoft 365 family' to 'Microsoft 365 Personal', it is not going to make any change to your files/data however, you would not be able to share your subscription with other users.
Please note that Microsoft 365 Personal allows you to install the same subscription on total 5 devices managed by a single user with 1 TB of storage space on OneDrive. On the other hand, Microsoft 365 Family allows you share the subscription with additional 5 users, who can manage up to 5 devices each with 1 TB of storage space for each user.
Should you have any counter question, please post it on this thread.
Thanks!