You can have apps, documents, folders, or server connections open automatically whenever you log into macOS High Sierra.
To add or remove automatic items, choose Apple menu > System Preferences, then click Users & Groups. Select your user account, then click Login Items at the top of the window, then do one of the following:
- Add a login item: Click the Add button (a plus sign) below the list of items, select a document, folder, app, server, or other item, then click Add.
- Remove a login item: Select the name of the item you want to prevent from opening automatically, then click the Remove button (a minus sign) below the list.
- Hide a login item: If you don’t want an item’s windows to be visible after login, select the Hide checkbox next to the item. (Note: Hide does not apply to servers, which always appear in the Finder after login.)
To temporarily prevent items from opening automatically when you log in:
- If you see the login window, press the Shift key while you click the Log In button, then release the Shift key when you see the Dock.
- If you don’t see the login window, restart your Mac, hold down the Shift key when you see the progress bar in the startup window, then release the Shift key after the desktop appears.
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)