Slipping straps are almost 100% avoidable

[Busted (and happy)]

From advice given by  my Bra fitter and personal experience  the only reason straps slip is that they have not been adjusted properly.

Slipping usually occurs when sitting. Hence it is fairly common to see a group of ladies sitting having coffee and nearly all of them regularly hiking bra straps.
(An avoidable annoyance!!!  Drives me mental just to see) 

I was advised  to decide how much to tighten them when sitting. If you adjust like this they will not slip. This will result in a tighter fit when standing that you will soon get used to unless you  over do it.  Basic rule is 80% of support from the band and 20% from the shoulder straps. If you over tighten the latter, believe me you will be the first to know - Sore shoulder skin and heavily red marked skin. Just a little trial and error needed

[blad]

Some bras are just made to be miserable in this department by having the strap anchor points at the back be too laterally positioned. 

[Rich meier]

mine problemis with the pullovers no adjusters

[Busted (and happy)]

One reason ditched pullovers, but each to his ownI

[Orb]

That is great advice.  I never really put it together.  I would always make adjustments while standing getting dressed, then would find things slipping like you say while sitting.  I would then have to go and make adjustments.  Keeping the right amount of tension on the shoulder strap is crucial.  Not to tight yet tight enough.

[Rich meier]

One reason ditched pullovers, but each to his ownI

thanks for the advice and new thread.my problem is 12 years ago I had shoulder surgery and 1 side is lower. I have bras with adjusters but having trouble getting the right size. the ones i have the band is good but the cups are to big even thou thats what the charts say. I am thinking of getting the next smaller band size and use extenders them maybe the cups might be better. the only other choice I see is get inserts or forms to fill them out. now I know why women complain about slipping straps. the only good thing is I wear t shirts so it is easy to reach under and pull it up

[Busted (and happy)]

Was a radiographer I one of my previous lives. Fully understand the difficulties you have from different angles. Hope you manage to find some sort of compromise that works for you 

[Rich meier]

thanks. i want to talk to  the advisors on herroom and see what they suggest

[42CSurprise!]

I have a slightly different problem with brassiere straps slipping off my shoulders.  When I first purchased a brassiere, about two years ago I bought one on E-Bay that was too tight in the chest.  The unlined cups and underwire design shaped my breasts perfectly however and the cup material was sumptuous.  Unfortunately, that brassiere didn't come in a larger band.  I tried other brassieres with some success but I thought it might be worth checking an extender on that first bra.  That solved the problem with the band but the extender moved the straps out on my shoulder and they regularly slipped off.  I'm at home so there is no problem adjusting them when needed but my success with the extender prompted me to look for a device that would keep the straps from slipping.  That was easy to do.  Now I wear that first brassiere as well as the others I bought in the same style and size, but different colors and my breasts couldn't be happier.  It is the Lilyette® by Bali® Dreamwire Plunge Into Comfort Minimizer Bra shown below.