You need to configure SDL Trados Studio for both the automatic confirmation of 100% matches and the confirmation of exact match segments.
Automatic confirmation of 100% matches for ITD files If SDL Trados Studio automatically confirms 100% matches, the status of the segment will be “confirmed” in the returned ITD and the reviewer will not be able to distinguish between segments that originated from the translation memory and those that you worked on. To prevent SDL Trados Studio from confirming all the 100% matches in the downloaded files, you should disable this option to make the reviewer's job easier.
Confirmation of exact match segments If SDL Trados Studio automatically confirms exact match segments, the status of the segment will be “confirmed” in the returned ITD and the reviewer will not be able to distinguish between segments that originated from the translation memory and those that you worked on. To prevent SDL Trados Studio from confirming all exact match segments in the downloaded files, you should disable this option to make the reviewer's job easier.