Why my auto-fill is like broken?

[BaiPiaoKer]

I types May 1, 2022, and May 2, 2022, then I auto-fill. The result comes out like this which is very weird. I also notice that I am not able to format the date by clicking right button and use the format cells function to change it to, for example, 5-1-2022. 

[#2]

@BaiPiaoKer 

It looks like Excel sees the values as text.

Format F1 as mmmm d, yyyy

Enter 1-May-22 in F1

Then fill down

[#3]

@BaiPiaoKer 

Check the smart tag:

[#4]

The number changes correctly, but I am still not able to use the format cell to format. After I click OK, nothing happened.

[#5]

@BaiPiaoKer 

You entered 1 May 22, but your system date format is in Chinese as far as I can tell, so you should enter the date in a Chinese format.

[#6]

@BaiPiaoKer 

In addition, you may enter the dates in ISO format like 2023-05-01, it shall be recognizable independently of regional settings.

One more, if you see your "dates" are left aligned that means you have texts which looks like dates. Dates actually are numbers and by default shall be right aligned.

Finally. applying another format to the cell you do not convert text to date/number, you shall to re-enter the value in proper format.