How do I install packages in PyCharm for all projects?

This is depending on your project settings, the project interpreter to be specific.

The project interpreter can be set to one of the following:

• an interpreter installed globally on your system
• an interpreter in a shared virtual environment
• an interpreter in a virtual environment associated with a project

Now the approach I'd recommend would be to create a shared virtual environment where you install your packages to, and use this environment for all your project.

That way, you have the desired result of needing to install your packages only once, but still have an environment isolated from your system environment.

To create such an environment, follow these steps:

1. Settings -> Project -> Project Interpreter
2. Click the cogwheel / gear icon right-side the interpreter dropdown
3. Select "Add Local..." -> Virtualenv Environment
4. Select a path as a root directory for the new environment
5. Select base interpreter you want to use
6. Tick the checkbox "Make available to all projects"
7. Click the "OK" button to save the new environment

You can download Package from the Pycharm IDE

1. Open Pycharm and Go to File
2. Click on Settings
3. On left Side, You will find Projects Option. Click & Expend it
4. Click on Interpreter 
5. A list of installed package will be shown
6. On Right Side, You will see a + button. Click This to install new package
7. A window will appear with Search bar, then search your package name and hit install button.

All steps are taken from this One minute Video.