The SSH or remote command operations will always try to find the "command" variable first before using any constants you define. If you are putting in multiple operations of the same kind the command input from the first operation will by default be passed to the next.
To change this behaviour. Open the command flow variable, then under "Assign From Variable" select not assigned. Then use the constant string that you like.
Alternatively, you could create custom command names within your flow and assign from those.
Whenever a sub-flow or operation runs, it will pass on any variables that it had to the next step.