Color change

[MarciSK]

How do I switch my yarn color without having a knot showing 

[NCcountrygal]

5 different ways.  5 BEST Ways to Change Color in Crochet • Sewrella

[Granny Square]

I never tie a knot as my only join method, only sometimes a temporary one to keep the fabric from falling apart for the first few stitches, but later weave the 2 ends back and forth invisibly in several directions for several inches so it's never coming out again.

The Russian Join (in the above link) is great, I also use the braided join, at the very end I weave in the last of the tails like the Russian join--these are mostly when I join in the middle of a row or round, not changing colors every row for a striped item--there I usually just weave in the ends securely later, in multiple directions.  No knots.  Seriously.  I'm talking about weaving at least 6" of yarn if you are working with worsted weight.  Sometimes I split the plies into 2 strands and weave them separately, they are never coming out that way.