Hi,
Thank you for your enquiry.
You could achieve this by installing a dedicated Welsh font type which includes characters with tobachs.
The following web site offers a free font pack containing two such fonts, Sophia and Doulos (which are similar in style to Arial and Times New Roman). Simply install these fonts into the Windows fonts directory (C:\Windows\Fonts).
http://www.wycliffeassociates.org.uk/dl-welsh.html
To import one of the tobach characters into your publication, simply click QuickBuild > Text > Insert Characters and select the accented W or Y character as required.
I hope this helps. Please do not hesitate to contact me if you have any further queries.
Kind regards,