I have recently experienced newly opened or created spreadsheets having a series of rows that present their entries upside down, often in reverse order and are not able to be deleted. If copied to a new sheet, the problem carries forward. I am concerned about this problem spreading to existing files and am currently unable to do new work on Excel. I am running Office 360 with auto update on a Mac Book pro. Excel says it is version 16.54. I've used Excel for a very long time and never seen anything like it, although I see some references in past forum postings to this problem. Those suggested updating Excel, which seems not likely the problem here. Any thoughts and guidance would be appreciated.