Nvcc show different version after restart the computer

Hello,

I tried to install CUDA 11.2. When I set the PATH export PATH=/usr/local/cuda-11.2/bin${PATH:+:${PATH}}, then nvcc shows:
nvcc -V
nvcc: NVIDIA ® Cuda compiler driver
Copyright © 2005-2020 NVIDIA Corporation
Built on Mon_Nov_30_19:08:53_PST_2020
Cuda compilation tools, release 11.2, V11.2.67
Build cuda_11.2.r11.2/compiler.29373293_0

However, when I restart the machine, nvcc shows older version
nvcc: NVIDIA ® Cuda compiler driver
Copyright © 2005-2015 NVIDIA Corporation
Built on Tue_Aug_11_14:27:32_CDT_2015
Cuda compilation tools, release 7.5, V7.5.17

nvidia-smi works fine before and after the restart
nvidia-smi
Tue Feb 2 11:23:29 2021
±----------------------------------------------------------------------------+
| NVIDIA-SMI 460.27.04 Driver Version: 460.27.04 CUDA Version: 11.2 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|===============================+======================+======================|
| 0 GeForce GTX 1060 Off | 00000000:01:00.0 On | N/A |
| N/A 51C P0 25W / N/A | 394MiB / 6073MiB | 0% Default |
| | | N/A |
±------------------------------±---------------------±---------------------+

±----------------------------------------------------------------------------+
| Processes: |
| GPU GI CI PID Type Process name GPU Memory |
| ID ID Usage |
|=============================================================================|
| 0 N/A N/A 1086 G /usr/lib/xorg/Xorg 286MiB |
| 0 N/A N/A 1919 G compiz 96MiB |
| 0 N/A N/A 2935 G /usr/lib/firefox/firefox 1MiB |
| 0 N/A N/A 2976 G /usr/lib/firefox/firefox 1MiB |
| 0 N/A N/A 3018 G /usr/lib/firefox/firefox 1MiB |
| 0 N/A N/A 3066 G /usr/lib/firefox/firefox 1MiB |
| 0 N/A N/A 3198 G unity-control-center 1MiB |
±----------------------------------------------------------------------------+

Could you please let me know why nvcc changes like that? Thank you!