Why do I have to enter my password everytime I update an app?

I'm running itunes for windows 12.1.2.27 64bit on a win7-64 PC

Since a recent update I now have to enter my apple account password every time I download any app update.

I used to just go to apps > updates tab and click 'check for updates' and then click 'Download updates' Now after clicking 'download updates' I have to enter my password, click 'download' in the password box and then click 'download updates' yet again every time!!

Can anyone tell me how to get this to revert to normal please?

thanks