Holes when changing colors in work

I have been knitting for about 40 years and have always leaned toward texture pattern sweaters and only occasionally doing multicolored ones. It’s very frustrating when I do one though because I always have trouble with the holes when switching yarns. My tension is very consistent but invariably the holes appear or the first stitch separates from the rest. I have followed all of the books I have researched and videos but it seems the harder I try the worse it gets.

Anybody have any suggestions?

Thanks.

Usually the problem is not crossing the two colors of yarn when changing colors. Bringing the new color up over the old color prevents holes and links the sections together. I would guess you’ve seen that twist of the yarn in the videos and in the books you’ve already looked at but just is case, here’s a video on intarsia and one on fair isle from the KH site.
You could tighten up the tension just a bit for intarsia but putting more tension on fair isle just makes it pucker.