Use Block Mode at the longer time bases. The capture is probably distorting due to a lack of sample rate from the switch to streaming mode at >100ms/div. Using block mode collects the data at full speed into the internal buffer and then transfers it to the PC in blocks. This allows the scope to maintain sample rates at the longer time bases.
This is found in Settings/Options/Advanced.
Tom Roberts
(The Picotologist)
http://www.autonerdz.com skype: autonerdz
THE PicoScope Automotive Authority
In North America