How to customize this search result?
I would appreciate any idea. Thank you.
Quick way to solve this is to make sure a Title property is available and filled in for each item in your list, that's what the Search page uses by default.
Otherwise you can modify the item display template, that will allow you to customize the display of search result snippet. There is a great article here on that process.
You can also set crawl rule for search query to show only files:
According to my research, you cannot customize the modern search in SharePoint Online.
The modern search text box is visible on the top header of the SharePoint. Microsoft search can be managed through Microsoft 365 admin center, but the admin cannot customize the modern search experience UI.
Generally speaking, click on the modern search text box will display 4~5 list items.
Please perform the following troubleshooting:
1.Does the list have multiple items with the same title/name?
2.It may be that items have not been search crawled, so these items cannot appear in the search box. It is recommended that you wait for a while (up to 24 hours)