@ZaneChiwawaUTAU ,
Thank you for showing before and after data in the code blocks.
You have to use a feature called “regular expressions”.
In your instance, it looks like you want to put your character right before the first comma in each line.
FIND WHAT = ^([^\r\n,]*),
REPLACE WITH = $1強,
SEARCH MODE = Regular Expression
The FIND of the regular expression will look for the beginning of the line (^), followed by 0-or-more (*) of the characters that aren’t CR, LF, or comma ([^\r\n,]), followed by a comma. Everying inside the (...) parentheses will go into group#1 for storage
The REPLACE starts with the contents of group#1 ($1), which will be the first field of your line, followed by the literal text 強, followed by a literal comma.
This is just one of the multitudes of things you can do with Regular Expressions. Look up each of the tokens I shared in the online User Manua’s Searching/Regex section linked below, to learn more about what they do, and to see other similar things that can be done.
Useful References
Notepad++ Online User Manual: Searching/Regex
FAQ: Where to find other regular expressions (regex) documentation