I want to filter by Patient ID which will show me all the observations of a specific patient every time I would appreciate guidance from experienced people! Thanks

Hello and welcome! This is the documentation on how to do a search https://www.medplum.com/docs/search/basic-search#searching-by-reference If you want to see it in the app you can use a URL like so https://app.medplum.com/Observation?subject=Patient/