One way that I was able to make BIAB always start in the same position in Windows (10), was to use an external software program that forces a window location to be remembered. A search engine can find programs or registry edits that will do this.

I tried unsuccessfully for years to do this within BIAB, as well as trying to use program shortcut properties in Windows. As someone else in this post suggested, there is probably a registry hack that will do this.

The program that I accidentally discovered for saving the BIAB window size and position was CamStudio v. 2.7.2 (free). This program records AVI video of portions of the screen, where it is desirable to have the same portion of the screen within the recording window.

Steps to make the BIAB window position return to the same place.

1. Start BIAB and resize the window where you like it.

2. Start CamStudio and click Region > Fixed Region, then drag a window around the BIAB window (it seems that the lower-left corner may be one of the corners that is used to remember the position).

3. Step 2 might be all that is needed, but I use a 3rd step, which is to make a recording of the BIAB region that will confirm the BIAB position. Click the orange star if necessary in CamStudio to set the recording mode to AVI mode. Then click the record button in CamStudio, and then confirm the window position before the recording begins. You do this by dragging the marquee that comes up to the same region identified in step 2. You can stop the recording and it will ask to save it. I saved it to a dummy temporary file name.

4. Close CamStudio. Close BIAB. Next time you open BIAB, even without CamStudio, the last position will be remembered. From this point on, the BIAB window position is independent of CamStudio, since BIAB comes back to the last position, not the one set with CamStudio.

Anyway that was my experience. Maybe the internal BIAB movie mode can also force this setting, but I haven't tried that.