how do you enable offline mode for mycareer?
make sure your internet is off before playing/on steam change to offline mode.
When you start and create your mycareer it will start in offline.
You can select it later on by pressing 'Y' buttom x-box controller (not sure the keyboard button) and select your off line user.
to get the 99 attributes to work do you have to have be offline? I mean my career is not "online" since its single player, or does it have to be offline to work?
Despite my Career being "single player" the player attributes and pretty much everything associated with it and VC is stored server side (might have something to do with mycareer being a grind with a handy Pay real money for VC short cut). That being said a number of options can be changed actually mid match as long as it doesn't directly impact VC. You can raise your attributes and lower your opponents to make VC earning plays easy (steals, blocks, etc); but you cant simply edit your block numbers it will show you having got them during the game, but they will immediately drop to accurate numbers once the match is over.
Edit: Sorry, just realized I didn't answer the specific question, the ignore attribute, 999 upgrades, attributes cost nothing (not sure which you where specifically referencing) is offline only. Note as of 3:00 GMT 10/06/16 game has been patched that broke some features even for offline. Update request has already been submitted.
[Edited by Evocati, 10/6/2016 11:46:27 AM]