Hi,
if you use tmux you could notice that every time you create new window it starts in the directory where you initiated your Tmux session.
Usually I start my Tmux at home directory but when I work for a project I like to have all my windows to be opened in this particular project.
Sure I can close the session and start the new one from the project directory but... no.
The way you can do it from withing Tmux is press your `<prefix>+:` to open the command mode.
Now enter `attach -c <your-default-start-directory>`. That's all.
It works outside of Tmux as well. You can run it this way `tmux attach-session -t <you session> -c <your-default-start-directory>`.