Need help with tictactoe game(C)

I'm not sure what is wrong with it but when i enter cetain coordinates it puts X's on multipul squares.I am pretty new to programming so go easy on me.
T.c
tictactoe.h

• Your if statements are wrong, you probably meant to use "==".
• Don't put function bodies in the header file
• Don't capitalize function names, that's standard for macros.
• Find a new way to check for winner. Your "if" statements took up eight wrapping lines on a standard 80-character window.
• You're declaring a global board[3][3] in both files, and they are different variables. Learn how to pass variables, and declare it in main.
• You aren't error checking. If someone enters 4, it'll go out of bounds and probably crash.
• You're using flaggy code, and that's poor style.

Fix these things, and we can help you with the actual issue.

Thank you for you answer. I didn't realize that I had a single equals sign in my if statement.