Now, I don't find myself in a position to object to the more experienced and expert commenter above but I found the following information in the 1000L series manual which can be viewed here:
http://unitrend.oss-cn-hongkong.aliyuncs.com/upload/file/20210530/UTD1000L%20Series%20User%20Manual%20REV1.pdfOn page 30 (document numbering) there is the following info:
"4.25 Autoset for Signals with DC Offset
UTD1000L Series is designed with powerful autoset function that makes it possible to perform fast and accurate measurement in DC–coupled mode for signals with any DC component."
Not sure if that is in any contradiction with what the above responder noted.
Also there are some more additional notes on AC/DC coupling in the manual that can be relevant to that feature:
p.20:
"Under AUTOSET mode, the coupling mode of the channel is closely connected to DC autoset; When DC autset is set to off, all signals in the channel is AC-coupled. If DC autoset is on, the channel will choose the current setting as coupling mode, when the current setting is DC coupling, the signal will be DC-coupled and vice versa."
p.28:
"The screen displays both AC and DC voltages if the oscilloscope is set under DC coupling. If only the small AC signal mixed in the DC signal is expected to display, please select AC coupling mode."
... and a few more mentions of coupling.