Hi Makoto:

The 1st part: >”You created a new MySQL file and a PLSQL file and saved them both with a .sql extension” <–Yes
The 2nd: > “You switched to the MySQL file, then created a new PLSQL file” <– not switched but created a new using say the MySQL configuration,
Lastly > “The previous MySQL document changed to PLSQL configuration” <– Yes.
It was back then the latest stable. I upgraded two minor once, but do not know if the issue remains as I did not work yet with SQL. But I plan to.