turning off Excel 'read-only' for documents already created

Hi all.
Every time I open a new Excel worksheet, I can only open it in 'read-only'. How can I (a) open a new worksheet not in 'read-only' (or better, how can I turn off the **** thing permanently), and (b) how can I convert existing read-only to not 'read-only'. Any help > thx. (PS using Excel 14.2.1)

If the sheet is not protected (locked) you can right click on it, select "Get Info" and at the bottom you'll see the permissions box. Change it to read write. However, on a sheet that's locked, you won't be able to make permission changes without the password. If you're opening a new sheet and it's already write protected, then you may have something set in the Office preferences. Open Office preferences and select "security". Make sure you don't have "read only recommended" checked. And by the way, you're behind several Office updates. Current is 14.5.9.

Thanks, chscag.
Unfortunately, there are problems with my enacting your instructions. Right-clicking does not bring up 'Get Info', and when I go to 'Security' in Preferences, there is no mention of 'read-only' or 'write-only', let alone anything to click on. Appreciate the notice re lag in OS though.

Right-clicking should open a dialog window. One of the options in that window should be "Get Info." If your mouse is a one button and you haven't configured for right-click, then hold CTRL and click on one of the xlsx files with the problem. That should open the dialog window.