What settings must I change so that .xlsx files I open from our company's network do not open without editing enabled.
There is nothing inherent about an "xlsx" file that would prevent it from being edited. Typically, if you are unable to edit it, it may mean that someone set the Properties on the file to be "read-only" (right click on the file from Windows Explorer and select "Properties"), or someone already has it open so it is opened in read-only mode (in which case, you would need to kick them out or make the file a shared workbook if you want multiple people to open and edit it simultaneously).
Also, if I open a .xlsm file, what settings will insure that the macro will always be enabled and ready to go? I can't seem to figure it all out. Thanks.
Take a look at the Security Settings (Excel Options -> Trust Center). There are a few different ways to do it (all workstation specific - you cannot force it down with the file itself).
1. Set the Macro Settings to "Enable all macros". This is probably the worst option, and I would not recommend it, as it would allow all VBA code to run, even malicious virus-type code.
2. Add the location of the file to Trusted Locations. Any files in these trusted will automatically allow/enable macros.
3. Create a digital signature and sign your macros. Then the first time you open it, when you get the Macro warning, click "View Certificate" and install the certificate on your computer and elect to trust all files signed with this signature. Then all files signed with that signature will automatically enable macros on that computer.