For Google Apps triggers (eg. in Google spreadsheet), please create them with the user hdx.gapps.triggers@gmail.com from Logins.
The reason is that it is not possible to see another person's triggers so multiple people could mistakenly create the same trigger on a spreadsheet.
Note that the hdx.gapps.triggers@gmail.com user only needs read access to the spreadsheet for the purposes of the trigger. Write access is only needed for adding the code for the trigger to the Script Editor (which can be completed with a different user). If the hdx.gapps.triggers@gmail.com user only has read access, you will not be able to open the Script Editor from the spreadsheet, you will need the direct url (which you can get by opening from the spreadsheet with another user that does have write access).