2006 Toyota Corolla transmission issue

[Corolladriver266]

My 2006 Toyota Corolla about a year ago was having issues shifting gears, it would rev up to 5 rpm while going 20mph. It showed a check engine light code p0500 (vehicle speed sensor ), I then changed the sensor and the car worked fine for a month, then the same code came up again and once again I changed and it worked good for about a month. Then after the second time changing the vehicle speed sensor a new code came up p0756 ( shift solenoid b is turned off/stuck). This code has been coming up for about a year now, but as the car heats it shifts gears perfectly. This code continuously comes on and then goes away by itself. I also tried putting new transmission fluid in and that worked for about 2 weeks and then the problem began again. Anyone have any insight on this problem?