I don’t recall the selection filter for earlier Kicad versions, but in 8:
The Schematic Editor has two filters, one for Libraries and one for Symbols in the selected library.
The Symbol Editor has only one filter for symbols in any library.
What you can do to make life much easier for yourself is to move your Personal Libraries to a more convenient place in the library list: eg. at the top.
This can be done by changing your personal library “Nicknames” or “Pinning” your personal libraries.
See towards the bottom of this FAQ for full details.
What is your Operating system; in case others wish to comment on changes between Kicad 8 and earlier editions?