On a printed or PDF invoice one of the fields shifts position but in the template editor it is correctly placed

Within SliQ's invoice template editor a number of types of condition can be set on a field. One condition type is the offset condition. The offset condition allows you to move the position of a field depending on the value of another field. See here for help:
The standard templates in SliQ use the offset condition to move invoice and quote total values depending on whether the business is VAT registered - moving the total field up to avoid a gap if no VAT value will be output.
A number of other conditions can be set for fields. See Setting Conditions on Template Items for links to help on all condition types.