I had a similar problem years ago. As I recall, Google Sheets interprets dates entered based on the locale of the user, not of who created the sheet. It's certainly a problem when collaborating across locales. On 9/3/16 8:13 AM, Syd Bauman wrote:
I used Chromium Web Browser on Ubuntu to edit our spreadsheet of arrivals and departures: https://docs.google.com/spreadsheets/d/1lfA50neSm_2tnX0qQj1vw9MhM3fgjN7WVOhf...
I wrote "Sat 09-24 10:10" into column B, and "Sat 10-01 10:25" into column C. In column B what I wrote was entered. In column C what I wrote was interpreted as a date and entered as "10/01/2016 10:25:00". However, it is displayed as "Sun 10-01 10:25". I'm betting this is because the date is interpreted as a European format date: January 10th was, in fact, a Sunday.
Furthermore, the string displayed in C was right-justified until I over-rode that with explicit formatting.
I'm guessing that "09-24" was not thought of as a date because "24" is not a possible month. I'm wondering if Google *always* thinks of dates as DD[sep]MM, or it does that because a European initiated this spreadsheet? (Who initiated this spreadsheet?)
Anyway, I've inserted some words to prevent Google Sheets from thinking of these as dates.