Restarting after each separate installation isn’t necessary unless you hit some instability and Notepad++ crashes I have never seen this happen.

You can either load them all and restart or do it individually, it’s up to you. You may be prompted to allow Notepad++ to restart after each install. Just find the plugin file you want, and copy the files to the Notepad++ directory on your computer. If you don’t wish to use Plugin Manager, you can still download plugins by hand from Github or other hosting sites. Simply find any of the below you want to add, check the box and install. There is no need to go elsewhere to download these plugins as they are all included in the Plugin Manager. Once installed, go back to Plugins and enable the one you just installed.In the main window, all you need do is check the box next to a plugin and select the Install button.This will let you know what to expect with any plugin you add. Select Settings in the bottom left and check the box next to Show unstable plugins and click OK.

You should see a new window appear with a selection of plugins.

Select Plugin Manager and then Show Plugin Manager.

Notepad++ plugin manager update