Hi Rod, nice pictures showing the problem.
Since version 4.1.0 the user can create multiple text Outputs. Due to this, the script commands have been expanded, to distinguish between the Outputs. Complete reference can be found in extsrc.pdf, section 'Dynamic configuration of the External Text Sources'.
Your Output ID is 1, so in your case, correct commands would be
set Output1.SrcSequenceItem3Checked:"0"
set Output1.SrcSequenceItem4Checked:"0"
set Output1.SrcSequenceItem5Checked:"1"
etc.
For example, the SrcSequenceItem5 is the fifth item in the sequence, from the top of the box. It is not the ID:5 because you may insert each source several times to the output sequence and you can still control each item separately.
Also the workaround with the NAText is no longer required. If you create a Source as Internal channel type, then you can set the text content directly from the Task Scheduler
set Source6.InternalChannelText:"TOTAL FIRE BAN"
The 'Tasks' box contains a set of button presets where the commands mentioned above are included, so you don't need to remember them.