Hello Dark Night
The confusion over the usage of that and which is common. If the sentence doesn’t need the clause that the word in question is connecting, use 'which'. If it does, use 'that'. You can take the help of books as well. Let us consider the following example:
Our office, which has two lunchrooms, is located in Georgia.
Our office that has two lunchrooms is located in Georgia.
These two sentences are different. The first sentence tells us that you have one office and it is located in Georgia. Removing the clause of the two lunchrooms will not change the meaning of the sentence – it is just an additional information. However, the second sentence suggests that there are multiple offices but the one having two lunchrooms is located in Georgia. By removing the information about the lunchrooms, the meaning of the sentence will change.
Hope that helps...