Process content can exist in multiple versions, e.g. the Working Version or the Valid Version.
To switch between different versions of process content, use the version selection menu on the top right. The valid version is marked with (V).
If the version you want to switch to is grayed out, the process element you are currently seeing does not exist in that other version. To switch to the desired version, you first need to navigate to an element that does exist in that version.
If you only see the process version as text, you do not have the permission to see versions other than the valid version.