Do you know how to customize the name of careers corporation?

That would be a string override.

First you need to know what you are going to replace exactly:

1. open Strings_ENG_US (or whichever locale you have there) in s4pe,
2. copy and paste the whole text from the preview to your favourite text editor
3. search for "Dewey"; you will find line 5619: " 0x4D368670: Dewey, Cheatem & Howe Incorporated" - this is the key that the game is using to look up that text.

To create the actual override:

1. create a new package in s4pe (File > New), add a new resource (Resource > Add);
2. in the window that opens, type "stbl" in the Type field, 0x80000000 in the Group field, and something like "chesterwhammy_deweynewname" (something that contains your user name) in the Name field, then hit "FNV64", untick "Use Resource name" box, and change the first two digits of the ID that is now in the Instance field to 00 (for US English) or whichever locale code you need for your language;
3. select the STBL resource you just created (in the list at the left side), hit "Grid" (at the bottom), hit the button with three dots (at the top right of the window that opens);
4. Now in the "Key" field enter the key you found above (0x4D368670), in the "Val" field the new name you want.
5. Hit "OK"; Commit, save your package and put it in Mods.

For additional languages, just copy + paste that STBL resource and change the fist two digits of the instance (see locale code reference). You could also use something like this tool if you're going to do a lot of replacements / translations (but for a single string that seems a little like overkill).

For more info on how stbls work, what's behind the business with the user name in the hash, etc, see the Maxis CC guide.

Thankyou so much. Sorry for late reply, barely use this account again.