y/yr and a/â (and other mutation causing words) only cause mutations to the words which follow them, not to words which precede them.
cwmni is a masculine noun, so it doesn’t mutate after ‘y’ (the) but it will mutate after a (and) and indeed â (with), and in both these it’s an aspirate mutation, so it changes to chwmni.
… and Hendrik beat me to it! 
Diolch @siaronjames a @Hendrik.
Now I know what I have to do. And I promise I won’t “bother” anymore. I know those are very basic questions which I should be totally familiar with by now but when you start to do something you start to get kind of paranoya upon the basic things like mutations etc …
I knew cwmni is masculine and it actually doesn’t mutate but it still kind of didn’t seam totally right to me so I’ve asked. And, yes, in deed I’d make a major mistake which you’ve just prevented to happen.
Diolch yn fawr iawn.
Hwyl!
Tatjana 
You’re never a ‘bother’ @tatjana - I’m sure I speak for Hendrik too when I say we’re happy to help! (and neither of us will demand joint song-writing credit either! 
)
Just wondering if this SM is a typo:
“Beth ŷch chi’n ddweud, Elen?”
Context: largely colloquial Southern-sounding paperback detective novel, pub. 1970. I was expecting “dweud”.
Dont know much about grammar, and I could be wrong, but that sounds right to me. Probably the implied “ei” in front of the “ddweud”?
Aha! Your answer has reminded me of when I asked almost the exact same question nearly two years ago - and you’re absolutely right! [chagrin face]
Hi bawb - does cyffrous mean both excited and exciting? Diolch
I think “excited” (as in ‘to be excited’) is cyffro
Kindle Reader Problem.
If anyone can help, please see Random Stwff Topic (to keep this topic free).Many thanks in advance.
Edit: I think I’ve sorted it. To do with the zoomed size of font.
“myn brain i” - something like “Upon my soul!” “I do declare”?
Also: Ydych chi wedi sylwi mor gwic mae dyn dwad yn cael i neud yn ddeiacon? Am nad yw e byth yn dod â’i orffennol gydag e gwlei.
“Have you noticed how quickly an incomer gets made deacon? Because he never brings his past with him X.”
gwlei? - can’t find it in dictionaries.
‘Dweud Eich Dweud’ comes to the rescue! 
Apparently it means “I believe/I think” and it’s a S Wales form derived from fe goeliaf i
I would guess it is something about politics. GM doesn’t have gwlei but does have these:
gwleidiad = countryman
gwleidiad and gwleidyddiaeth = politics
gwleidydd = politician, statesman
gwleidyddol = political
(I do love Y Geiriadur Mawr just for such things!)
So what was this one?
The only thing that I’ve found would be something like " mynd ar brain" perhaps gone to the crows (gone to ruin).
Just a thought, if it’s SE Wales -
In Bristol, “Brain” = stoney (brazen) soil, but that’s English.
Yes, very similar - ‘myn’ here is ‘by’ as in an oath, so “By the crows!” (don’t worry about the lack of an y - this not a literal word-for-word phrase!)
Oh, OK - I’d found myn as in oaths/exclamations in the GPC, but didn’t quite believe it was “by my crows!” The same book has also provided myn asgwrn i - presumably “by my bone!”
Hi, I would appreciate some help with the translation of these words/phrases which I need to be able to speak about myself, my work and possibly also about SSiW:
I could translate the words using an online dictionary but I need some help with choosing the correct prepositions and mutations.
Thank you.
)Thank you. This makes me wonder, are the Welsh alternatives for Facebook/Twitter used?
some people use them, yes, but a lot don’t - it’s just personal preference. As long as you’re aware of them though, they won’t confuse you when you do come across them.