Blaze is Bosch's range rather than a single tool, so button positions differ between models. The operating logic does not, and neither do the three quirks that send owners looking for a fix that does not exist.
Blaze covers a wide spread, and the differences change what the tool can do rather than just how far it reaches.
Bosch quotes distance accuracy of plus or minus one sixteenth of an inch across the range, and levelling accuracy of plus or minus 0.2 degrees on models carrying an inclinometer. Models with the tilt sensor read angle across 360 degrees in two axes, which is what makes the indirect modes work.
Set the reference point. On a Blaze this is the small icon showing a rectangle with a mark at one end, and it decides whether the tool measures from its front edge or its back.
This matters more on Bosch than on some brands because the defaults are not consistent across the range. The GLM400CL ships referencing from the back of the device, and enough owners consider that the wrong choice that it comes up repeatedly in reviews, with more than one describing it as a firmware decision Bosch should revisit. Whatever your model does out of the box, set it deliberately and verify it.
The check takes thirty seconds. Measure a known span, flip the reference, measure again. The two readings should differ by exactly the length of the tool. The reference point has its own guide because it catches so many people.
Press the power and measure button once to wake the tool and fire the laser. Press it again to take the reading. On most Blaze models that is the same button, which is why a single press sometimes appears to do nothing: the first press turned it on.
Brace the back of the tool flat against your starting surface rather than holding it freehand. The backlit display is one of the genuine strengths of the range and stays readable in a dim basement or crawl space, which is where most owner praise concentrates.
For a live reading that updates as you move, hold the measure button to enter continuous mode. The tool tracks until you press again, and shows minimum and maximum alongside the current figure. That minimum reading is the trick for measuring a room diagonal accurately: sweep the corner and take the smallest number, which is the true perpendicular.
The function or mode button cycles through the calculation modes, with an icon on the display showing which is active.
Area asks for two readings and multiplies them. Volume asks for three. Both are worth using over doing the arithmetic yourself, because they remove the step where mistakes actually happen.
Indirect modes need a model with the inclinometer. They calculate a height you cannot shoot directly from two readings and the angle between them, and they only work if the tool does not move between those readings. Bosch's 0.2 degree levelling tolerance is the figure to hold that against: if your angle readings disagree with a spirit level by more than that, the tilt sensor needs recalibrating before the indirect result means anything. Indirect measurement is covered properly here, and tilt calibration here.
These come up repeatedly in owner reviews and none of them is a fault you can fix. Knowing about them in advance saves an evening.
Memory will not hold fractional inches on the GLM165-40. Recall a stored measurement and it returns in metric regardless of your display setting. Owners have worked through the manual, the available videos and the pinhole hard reset, and it persists because it is firmware behaviour rather than a setting. If you rely on stored readings in fractions, this is a real limitation.
The fractional digits are small. Several owners note that the fraction portion of the display is printed at a size that is hard to read at arm's length without reading glasses. The main number is large and clear. The sixteenths are not.
The GLM100-23 stores one measurement at a time. Owners upgrading from the previous generation notice immediately, because the older model held several. Nothing is broken, the capability was removed.
Indoors on a matte wall, these tools hit their numbers. Outdoors they do not, and that is physics rather than a Bosch problem.
Owners of the GLM100-23 describe it working well indoors and poorly in daylight. Even the GLM400CL, sold specifically as the outdoor unit, draws comments that the red dot disappears in bright sun. Bosch's answer on that model is the camera: you stop hunting for the dot and aim with a crosshair on the screen instead, which is the actual reason it works at 400 ft.
If you work outdoors regularly and do not want the 400CL, the GLM165-25G with its green beam is the more practical route. Green is roughly four times more visible to the eye at the same power, which does not extend the sensor's reach but does let you place the dot. The green beam comparison is here.
For model-specific button sequences, Bosch publishes manuals for each Blaze on its own product pages, and those are the authority for anything that differs between generations.
If you have arrived at the wrong page for what you need, start here instead.