Rearrange columns using cut
For the cut(1) man page:
Use one, and only one of -b, -c or -f. Each LIST is made up of one range, or many ranges separated by commas. Selected input is written in the same order that it is read, and is written exactly once.
It reaches field 1 first, so that is printed, followed by field 2.
Use awk instead:
awk '{ print $2 " " $1}' file.txt