Hi ,
when I am creating a new opportunity and trying to search the customer name it gives me a different result than expected . e.g when I am typing in 'Tech' it gives me following , and when I am typing in 'Tech M' it is altogether different . My requirement is when i type 'Tech' , it should give me all relevant result . Please refer to below screenshots from my demo. 
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Dear Shailey,
According to the application logic, the drop down list is useful if you know the company name, since the list of accounts or contacts on the opportunity minipage displays only 3 results sorter in alphabetical order. That is why you see only 3 accounts starting with 'A' character when typing 'tech'. The same way you see the 'Tech Mahindra' when typing 'tech m'. Since this account matches the condition 'tech m' you can see only 1 result.
Best regards,
Dean
Dear Shailey,
This logic is hardcoded and cannot be changed by the basic application tools. However, as a workaround, you can modify the minipage through the section wizard and add the account field with pop-up view type https://prnt.sc/nrq6pk . As the result, you will be able to see all the accounts from the list https://prnt.sc/nrq6w9
Best regards,
Dean