These lines of text are translated in the "lang.js" file
located in "C: \ Program Files (x86) \ TSplus \ Clients \ www \ software"
You can change the line:
translations ['en'] ['Reset your Windows password'] = 'Reset your Windows password';
in
translations ['en'] ['Reset your Windows password'] = 'Reset your Server password';
to see the desired text appear.
If you don't want this modification to be overwritten the next time TSplus is updated, meaning that you will have to constantly fix this line, change this file to "read-only".
However, by doing this, when TSplus is updated the updates won't be applied to the file (because in Read-Only).