Thank you for you prompt support! The replies you have given are more or less the ones which I had anticipated myself and unfortunately do not solve my problems. When I type in "iGO0" as the "Appid" and "/storage/sdcard0/iGO" as the "Memory path" pointing to the location of my themechanger directory and press the button "Test", I keep getting the red thumb down symbol (see the picture) and the bottom buttons remain grey and inactive.
It does not help playing around with the installation location of themechanger and swapping it between internal memory and external sdcard makes no difference - the result is always the red thumb down.
I would appreciate if somebody could report his/hers settings of a successful installation of Themechanger v7.0 and in particularly the inputs he/she has given to "Appid" and "Memory path" seen in the picture below.