the H8000 has almost 2000 presets, so the simple 1>128 program changes method won't be really useful to recall any of these presets. The unit presets are organized in Banks. There are several ways to work with such structure:
keep in mind that the H8000 will load presets ONLY from the current bank, that is the one you are looking at, on the display. To go beyond this:
-you may need a MIDI controller (pedalboard or else) capable of sending MIDI Bank Change message (CC #0) with the value of the Bank number you want to address, followed by a MIDI Program Change with the same number of the preset in that bank you want to load. This method will change Banks AND load Presets in any of them
-or you can use MIDI MAPS, a very advisable feature in the H8000. You need to refer to the latest OS User Manual to get all details about this method
Please check page "126 Loading a Program Via a MIDI Program Change Message" for all details to setup the H8000 for MIDI program changes.
all the best