It’s probably a good time to consider making some Personal Libraries in Kicad, otherwise just imagine what your library system will look like in 3 years:
Once you have some Personal Global Libraries your procedure will be to place symbols/footprints from other projects into Personal Global Libraries and then use those symbols/footprints in your projects instead of copy/paste directly into your projects.
Kicad is not shipped with libraries into which you can add parts. You have to create your own libraries: The Personal Global Libraries I mentioned above.
Kicad libraries are read only. To modify a Kicad supplied part, you must first move that part to a Personal Library or place it in a project first.
The real problem with using “modified in a project” Kicad parts or “imported from elsewhere” parts is future use of these parts.
The only way to re-use these parts in a future project is to find the Kicad project in which you originally used them or go back to their source and, in either case, copy/paste again (which results in yet more single item libraries).
How’s your memory, when, in two years and ten projects later, you want to find a part you used previously, for a new project?
Populating Personal Libraries is easy.
If you wish to place a Kicad library part into a Personal library you:
- Highlight the part in the Kicad Library.
- Right click that part and select “save as”
- Scroll to and highlight your personal library (change the name if you wish)
- Click OK and it is done.
If you wish to place a part from elsewhere into a Personal library, you need to:
Extract the content of the download
Open your Symbol or Footprint Editor
Highlight the Personal Library in which you wish to place the part
Right click Import or Paste (whichever is appropriate)
Navigate to the part
OK.
If you wish to move a part from one of your many created single part libraries to a newly created Personal library use the “save as” again.
Note: when you shuffle parts to and fro different libraries, the links to those libraries in the projects will be lost. The parts will stay in the projects but warnings will occur. The only way to remove the warnings is to restore the links to the new libraries. ie. delete symbols and replace with the same symbol but from the new library.
Using your current method of work will eventually result in a big mess. It is better to sooner rather than later change to a more organized library structure. This comments are from my own experience. I started much as you have and very quickly ended in deep excreta with my own libraries
I wrote FAQ on creating Personal Libraries here..
There is also the official version here and a good article on library manipulation here.