Mean Well power supply voltage adjustment
All PC PSU's started out with the intention of a minimum load sharing and so they used a common primary transformer coil and high mutual coupling so only one driver.  They usually needed 10% preload on 5V to work at all 20 yrs ago.  This was a major cost reduction.
Here in the fine print the specs are defined by Load Regulation error.  5V=1%, 12V=5% but with the other supply loaded with 60% and step load from 20% to 100%.
Your question needs a design load {Min:Max} as a spec for each channel and a tolerance.
It  can be 5% if you like or 10% if you show what you are doing or 1% if you expecting too much.  Just give the details and it can be sorted out.
This is also called crossload regulation error which is not given but can be figured out if you tell us what/why you need accuracy or low noise. This CLR error is often specified by better suppliers.

If you need 5% V tolerance on 12V from 20 to 100% step load, then the spec says you need 23W load out of 38.5W rated on the 5V rail.  So you may need a dummy load.  The less 5V load, the poorer tracking of 5V and 12V as a ratio from Pot adjust.