cant select subject

[JS_09]

sometimes work sometimes not

[AxelMatt]

Unfortunately you don't have gave us any informations about your system. So all proposed solutions are a guesswork.

Is your system up-to-date? Do you have installed all recent updates and patches for the operating system and the device drivers, especially the graphic driver. If you have a NVidia graphic card installed, make sure that you are using the recent Studio version of the driver, not the Game Ready version.

Please provide a copy of your 'System Info'. This can be get from the Photoshop menu item Help > System Info. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.

In the meantime you can try to reset the preferences of Photoshop using the steps described here:

https://helpx.adobe.com/photoshop/using/preferences.html#reset-preferences

Please backup your settings before resetting the preferences. You can check:

https://helpx.adobe.com/photoshop/using/preferences.html#backup-photoshop-preferences