Linking dynamic cell values to same textbox

I would be very pleased to accept any help to guide me over the following obstacle:

I have 2 VBA UserForms to help me work out prices/costs in order to quote for new projects. I want to use the Worksheet as a mini database so I can track, compare etc over time.

Both UserForms work with the same Excel Worksheet. UserForm1 takes textbox, combo, listbox data and populates specific columns on Worksheet. Data in these columns is used to return a variety of calculations on the same row of the same worksheet per my formulae in the relevant cells on the said Worksheet.

I can clear UserForm1 and add another set of details relating to the next project. All works fine and details of the next project are entered in the row immediately below that of the previous set of details.

UserForm2, is a 'Results' or an 'Outcome' form whose textboxes show some of the specific metrics that I need to capture in order to see the resource, price, direct and variable cost etc of the proposed project. That too works just fine.

However, as I add another project, the cell reference for Textbox1 on UserForm2 does not change - it stays at "AC2" (or whichever cell on the Worksheet applies). I need it to track down to "AC3" and so on as information for subsequent prospective projects are added via UserForm1.

I have tried to modify the Do...Loop which works perfectly well on UserForm1 as I mentioned above, but I am unable to achieve a similar success with UserForm2.

Many thanks in anticipation for some help and insight.