how to replace part of a string in batch script code example

Example: cmd substring replace

# EXAMPLE: first sets variable A, then replaces the 'aaa' with 'bbb', and then echos the new variable
set "A=text aaa"
set "B=%A:aaa=bbb%"
echo %B%

# SYNTAX
# set "<intial-variable-name>=<intitial-value>"
# set "<new-variable-name>=%<intial-variable-name>:<substring-to-replace>=<replacing-substring>%"
# echo %<new-variable-name>%