This is potentially a difficult problem to solve, especially if the code to change a variable is sprinkled all over the program.
If there are few statements that change the value of the variable, you can use the “Break When Value Changes” option when inserting a watch expression. This makes the program pause every time this variable or expression changes. Note that this approach can slow down the execution of the program significantly.
If there are lots of statements that change the value of the variable, or that the changes very frequent, then the “Break When Value Changes” approach is not practical. You may need to debug your program structurally.