Aastra time incorrect

I’m new to the FreePBX/Linux so please bear with me. I having issues trying to get the time correct on the Asstra (6757i) phones I have. I used this link as a guide but I’m not sure how to remove/replace the configuration file like the poster had to do.


They will however accept

time zone name: US-Pacific
time zone code: PST

for example, different strokes for different folks?