I found 2 new quirks. When I make a new session and set it up for Cab mode, when I start the session it is in easy mode. If I state for not being able to change it, then I am stuck in easy mode.
There are a combination of factors at play here.
Firstly, you're assumedly attempting to change the behavior using the QuickDrive rule or some close equivalent? If so, please be sure to use the "Restart All Rules" command (or perhaps right click and use "Reset") to ensure that this rule takes effect. Otherwise, since it has likely already run by the point where you're testing this, any rule configuration changes you make won't have any effect. You can check the current status of the rule on the right side of the rules list in "Edit Session". If it says "Complete", it has already done its thing and will not run again without some external trigger.
Secondly, as of TRS19 the cab/dcc/commands Control Mode is determined per Driver, not at the per-session level as it was in T:ANE and earlier. While the per-session state can still be configured (via Script, via the QuickDrive rule, etc.) this only effects Drivers as they are created, and cannot be used to reconfigure existing Drivers.
Given that you're talking about locking the user's ability to toggle this configuration (again, assumedly via the QuickDrive rule), if you change your mind about how things should be configured, here's what you'll need to do:
1. Surveyor > Edit Session.
2. Modify the QuickDrive rule to your desired configuration, and permit the user to change the configuration.
3. Restart All Rules.
4. Accept your changes.
5. Switch to Driver and unpause.
6. Cycle through each existing Driver, changing the UI of each into the desired Control Mode.
7. Surveyor > Edit Session.
8. Modify the QuickDrive rule to prevent the user from making further changes to the configuration.
9. Restart All Rules.
Beyond this point, your new configuration will be locked in for all the existing Drivers, you won't be able to make additional manual changes, and new Drivers which are created will adopt whatever Control Mode you have specified via the QuickDrive rule.
Yes, that's all a little complicated, but it's only happening because you've locked of the ability to change Control Modes and yet still want to change the Control Mode. If you didn't lock the mode in the first place, the user could just set each Driver to whatever Control Mode they feel like with the click of a button. If you're the kind of person who builds sessions where locking the Control Mode is important, then it shouldn't take you long to get your head around the above and include it into your workflow.
hth,
chris