Hi @Anonymous,
There is no cache for the data source under PowerApps. PowerApps queries data source directly when there is a request, such as a refresh, update or lookup.
For the old names, which field that you changed, under SharePoint list New View, or classic view?
Under SharePoint New View when changing the title field, the changed name won't be updated under SharePoint list, for the other columns, it works as expected from my testing.
Regarding the fields newly added, you might need to un-hide them under Viewform/EditForm:
Follow this document:
understand data forms in Microsoft PowerApps
If you have any further questions, please post back.
Regards