I use school pva glue from tesco , watered down 50/50 with water. Paint back of label, if you inkjet print runs you are using too much.
the labels soak Off easily in water.
good luck
I’ve been using these, and printing them out on my inkjet. A quick 15min soak in hot water and they just slide off. Any adhesive that’s left behind is easily removed with a scotchbrite.
Like @Cheshire Cat I identify by the colour of the cap, and have recently made a board using a £1.99 chalk board from the Range and small magnets for the caps so I can change them. Cost about £4 in total, plus the liquid chalk pens.
I saw an old post on this forum the other day where someone used an old printing press to make the label and milk to stick it on. It's the sort of thing I look at and think "life's too short" but then very quickly think "... now, where can I get hold of an old printing press..."