https://support.clarivate.com/Endnote/s/article/EndNote-All-search-results-automatically-entered-in-library-with-X2-and-later?language=en_US

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EndNote X2: First, verify you are running X2.0.1 or later by on Windows going to the help menu and choosing "About EndNote". On a Mac go to the EndNote X2 menu and choose "About EndNote"

If it still reads X2.0.0, get the EndNote: Version X2 Updates. EndNote X2.0.1 and later introduce the library window display modes. EndNote X2.0.1 and later: You can choose from different display modes in the Library window. 📷 With EndNote X6.0.1 for Windows and EndNote X6 and later for the Mac, the order and appearance of the icons will vary. The icons on the Mac will appear as follows:

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You may want to always work in Integrated Library & Online Search Mode, where all groups and commands are available. When you download references from an online database, they are saved directly into your open library. The other option is to work primarily in Local Library Mode and switch to Online Search Mode when you want to search and download references from an online database. In Local Library Mode, the Online Search groups are not available; once you select the Online Search command from the Tools menu, you are automatically switched to Online Search Mode. In Online Search Mode, only the Online Search groups are available, and references are downloaded into a temporary library. This allows you to download references from online databases without affecting your local library. Many library commands are not available in Online Search Mode. To switch between these modes, click on the appropriate toolbar button. For more details, click the EndNote Help option, select "What's New in EndNote X2" and choose "The Library Window Display Modes" or click on the Help option, select "Search of Help On" and browse to the "Modes" topic with EndNote X3 and later. Note: If you cannot upgrade to X2.0.1 or later at this time, EndNote X2.0.0 imports all search results directly into your library. Note that the references you do not want can be dragged into the "Trash" group to remove them from your library, or you can simply select them and choose "delete" on your keyboard to move them to the "Trash" group. This change was made to protect users from accidentally citing from search windows rather than from their reference library. If you would prefer not to directly import all search results, you could create a new library to use as temporary storage for the references. Perform searches within this temporary library, and then simply cut and paste or drag and drop your desired references into your master library.

thanks for your reply, but I still cannot figure out what to do...

I removed the ENDNOTE 20 and backed to use EndNote X 9.3.3.