In the last section of your Mapping step, you will find the following, where you can customize your Syncee updates.
In the first part, you can select the product details you would like to update every time when the task is run. Choose those fields that can vary in your source file.
Secondly, you can choose those fields that you do not want to update. Syncee will not update the selected fields when you run the import task.
If you want to learn more about the update options, read our article here.