Well, that's it, very much thanks to the perseverance of you two kind gentlemen and other forum members, all working well and looking good.
Yes, I was aware of the screen resolution change facility within the Raspbian, desktop shell but I thought as it had not changed from the "window 1" setup, still 720X480, then that might not be the best place to adjust.
However, increased in steps up to "DMT mode 16 1024X768 60 Hz 4:3" setting which is now virtually the same as previous when using the "window 1" setup.
Kept the startup, sleep delay at 3 mins, needed for my old slow RPi Mk1B which struggles a bit, CPU usage tops out during sampling and uploading to MDWS, however, it still manages to maintain 100% upload on MDWS so does the job.
Will now update the configuration on the two RPI Zero W's I look after to enable DSLStats auto-booting, as they both run on the exact same program as my Mk1B RPi (apart from IP addresses) should be easily done.
Again, many thanks to RichardB and vic0239 for the support and assistance provided.