Tiny UI same as issue "Very small UI #71"

[gmos64]

Couldn't reopen issue "Very small UI #71" so creating new one.

I've been using PIA for a few years, but have had a similar issue here for some time. Currently using LinuxMint Xia Mate edition on ACER Intel i7 laptop with 2880x1800 screen, Auto Scaling is on and works with everything else correctly, but both PIA GUI and Panel Indicator are too small.

I've looked at the previous answer ("PIA_SCALE=2 worked fine ") but after searching around, do not know how/where to set it. Could someone look into the cause of the problem, and also advise me of how to set the work around environment variable?