When i turn from veg to flowerimg mode it is advised or i read online that thru the day you should leave the temp below 85 and thru the night at 65f but i was wondering if i can just leave it at around 68 permanently until the the end of harvest when i cut down my plant will this cause any problems or is it fine, any advice i will appreciate it?
You can do that, but the growth will be stunted. Higher temps lead to more profuse growth. Get a cheap electric heater and an accurate thermostat control. Most built-in heater thermostats aren't very good, but if you can live with 10 F temp swings, the accurate thermostat isn't needed.