It would be useful to understand how you feel the new version is inferior to the older version, so that we can improve it.
The biggest change in version 4 is that you can do all the configuration you did in the old client during the session, while in version 3 you had to take a number of decisions before connecting to the remote server and, once connected, you could do very little. The initial GUI, by which you must choose the computer to connect to, is designed to be “dynamic”.
As for the select text issue, it would help to know what Windows version on the client you have installed, what Linux distribution and version you are using on the server side, what DE it is. What NoMachine products and version have you installed on client and server sides? (see list below “What to include”). We assume that you have Workstation installed on the server side.
We are aware of a problem with selecting text for which a TR is open https://www.nomachine.com/TR11K04089.