We are trying to remove the checkbox which appears when uploading a new document in SharePoint (we are using 2013).
By default this is checked. We would like it to be unchecked by default.
I have seen information on how to do this by modifying the upload.aspx and uploadex.aspx file (e.g. here: http://lazysharepointadmin.com/blog/2011/08/25/change-overwrite-existing-files-behavior/#comment-111 )
However, I believe the above is not recommended (as it could cause problems when upgrading).
I've also seen brief information on how to do this via an elements.xml file and using a delegate control..? But I don't fully understand where or how to do this and don't want to get things wrong on a master page.
Can anyone shed any light on how the AdditionalPageHead delegate control can be used to do this please?